flow: Annotate some more exported React components.

This is easier to do now that we've converted these to function
components in this series.

This will help move us along toward Flow's new "Types-First" mode;
switching entirely is zulip#4907.

Prefer the `Node` type exported from React over `React$Node`.
They're equivalent, but Greg prefers `Node` as it seems cleaner; see
  https://chat.zulip.org/#narrow/stream/243-mobile-team/topic/Flow.20types-first/near/1239060.

src/account-info/AccountDetails.js

@@ -1,5 +1,6 @@
 /* @flow strict-local */
 import React from 'react';
+import type { Node } from 'react';
 import { View } from 'react-native';
 
 import type { UserOrBot } from '../types';
@@ -33,7 +34,7 @@ type Props = $ReadOnly<{|
   user: UserOrBot,
 |}>;
 
-export default function AccountDetails(props: Props) {
+export default function AccountDetails(props: Props): Node {
   const { user } = props;
 
   const ownUser = useSelector(getOwnUser);

src/account-info/AccountDetailsScreen.js

@@ -1,5 +1,6 @@
 /* @flow strict-local */
 import React, { useCallback } from 'react';
+import type { Node } from 'react';
 
 import type { RouteProp } from '../react-navigation';
 import type { AppNavigationProp } from '../nav/AppNavigator';
@@ -30,7 +31,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'account-details', {| userId: UserId |}>,
 |}>;
 
-export default function AccountDetailsScreen(props: Props) {
+export default function AccountDetailsScreen(props: Props): Node {
   const dispatch = useDispatch();
   const user = useSelector(state => getUserForId(state, props.route.params.userId));
   const isActive = useSelector(state => getUserIsActive(state, props.route.params.userId));

src/common/ZulipStatusBar.js

@@ -1,6 +1,7 @@
 /* @flow strict-local */
 
 import React from 'react';
+import type { Node } from 'react';
 import { Platform, StatusBar } from 'react-native';
 // $FlowFixMe[untyped-import]
 import Color from 'color';
@@ -42,7 +43,7 @@ type Props = $ReadOnly<{|
  * top inset grows to accommodate a visible status bar, and shrinks to
  * give more room to the app's content when the status bar is hidden.
  */
-export default function ZulipStatusBar(props: Props) {
+export default function ZulipStatusBar(props: Props): Node {
   const { hidden = false } = props;
   const theme = useSelector(state => getSettings(state).theme);
   const orientation = useSelector(state => getSession(state).orientation);

src/emoji/Emoji.js

@@ -1,5 +1,6 @@
 /* @flow strict-local */
 import React from 'react';
+import type { Node } from 'react';
 import { Image } from 'react-native';
 import { createIconSet } from 'react-native-vector-icons';
 
@@ -23,7 +24,7 @@ const componentStyles = createStyleSheet({
   image: { width: 20, height: 20 },
 });
 
-export default function Emoji(props: Props) {
+export default function Emoji(props: Props): Node {
   const { code } = props;
   const imageEmoji = useSelector(state =>
     props.type === 'image' ? getAllImageEmojiByCode(state)[props.code] : undefined,

src/emoji/EmojiPickerScreen.js

@@ -1,6 +1,7 @@
 /* @flow strict-local */
 
 import React, { useState, useCallback } from 'react';
+import type { Node } from 'react';
 import { FlatList } from 'react-native';
 
 import type { RouteProp } from '../react-navigation';
@@ -24,7 +25,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'emoji-picker', {| messageId: number |}>,
 |}>;
 
-export default function EmojiPickerScreen(props: Props) {
+export default function EmojiPickerScreen(props: Props): Node {
   const { route } = props;
   const { messageId } = route.params;
 

src/message/MentionedUserNotSubscribed.js

@@ -1,6 +1,7 @@
 /* @flow strict-local */
 
 import React, { useCallback } from 'react';
+import type { Node } from 'react';
 import { View, TouchableOpacity } from 'react-native';
 
 import type { Stream, UserOrBot, Subscription } from '../types';
@@ -49,7 +50,7 @@ const styles = createStyleSheet({
   },
 });
 
-export default function MentionedUserNotSubscribed(props: Props) {
+export default function MentionedUserNotSubscribed(props: Props): Node {
   const { user, stream, onDismiss } = props;
   const auth = useSelector(getAuth);
 

src/message/NotSubscribed.js

@@ -1,6 +1,7 @@
 /* @flow strict-local */
 
 import React, { useCallback } from 'react';
+import type { Node } from 'react';
 import { View } from 'react-native';
 
 import type { Stream, Narrow } from '../types';
@@ -14,7 +15,7 @@ type Props = $ReadOnly<{|
   narrow: Narrow,
 |}>;
 
-export default function NotSubscribed(props: Props) {
+export default function NotSubscribed(props: Props): Node {
   const auth = useSelector(getAuth);
   const stream: { ...Stream, ... } = useSelector(state => getStreamInNarrow(state, props.narrow));
 

src/nav/ZulipNavigationContainer.js

@@ -1,5 +1,6 @@
 /* @flow strict-local */
 import React, { useContext, useEffect } from 'react';
+import type { Node } from 'react';
 import { NavigationContainer, DefaultTheme, DarkTheme } from '@react-navigation/native';
 
 import { useSelector } from '../react-redux';
@@ -20,7 +21,7 @@ type Props = $ReadOnly<{||}>;
  * - Call `createAppContainer` with the appropriate `initialRouteName`
  *   and `initialRouteParams` which we get from data in Redux.
  */
-export default function ZulipAppContainer(props: Props) {
+export default function ZulipAppContainer(props: Props): Node {
   const themeName = useSelector(state => getSettings(state).theme);
 
   useEffect(

src/streams/EditStreamScreen.js

@@ -1,5 +1,6 @@
 /* @flow strict-local */
 import React, { useCallback } from 'react';
+import type { Node } from 'react';
 
 import type { RouteProp } from '../react-navigation';
 import type { AppNavigationProp } from '../nav/AppNavigator';
@@ -15,7 +16,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'edit-stream', {| streamId: number |}>,
 |}>;
 
-export default function EditStreamScreen(props: Props) {
+export default function EditStreamScreen(props: Props): Node {
   const dispatch = useDispatch();
   const stream = useSelector(state => getStreamForId(state, props.route.params.streamId));
 

src/streams/InviteUsersScreen.js

@@ -1,5 +1,6 @@
 /* @flow strict-local */
 import React, { useState, useCallback } from 'react';
+import type { Node } from 'react';
 
 import type { RouteProp } from '../react-navigation';
 import type { AppNavigationProp } from '../nav/AppNavigator';
@@ -17,7 +18,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'invite-users', {| streamId: number |}>,
 |}>;
 
-export default function InviteUsersScreen(props: Props) {
+export default function InviteUsersScreen(props: Props): Node {
   const auth = useSelector(getAuth);
   const stream = useSelector(state => getStreamForId(state, props.route.params.streamId));
 

src/streams/StreamSettingsScreen.js

@@ -1,5 +1,6 @@
 /* @flow strict-local */
 import React, { useCallback } from 'react';
+import type { Node } from 'react';
 import { View } from 'react-native';
 
 import type { RouteProp } from '../react-navigation';
@@ -26,7 +27,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'stream-settings', {| streamId: number |}>,
 |}>;
 
-export default function StreamSettingsScreen(props: Props) {
+export default function StreamSettingsScreen(props: Props): Node {
   const dispatch = useDispatch();
 
   const auth = useSelector(getAuth);

src/streams/SubscriptionsCard.js

@@ -1,6 +1,7 @@
 /* @flow strict-local */
 
 import React, { useCallback } from 'react';
+import type { Node } from 'react';
 import { View } from 'react-native';
 
 import type { RouteProp } from '../react-navigation';
@@ -26,7 +27,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'subscribed', void>,
 |}>;
 
-export default function SubscriptionsCard(props: Props) {
+export default function SubscriptionsCard(props: Props): Node {
   const dispatch = useDispatch();
   const subscriptions = useSelector(getSubscribedStreams);
   const unreadByStream = useSelector(getUnreadByStream);

src/subscriptions/StreamListCard.js

@@ -1,6 +1,7 @@
 /* @flow strict-local */
 
 import React, { useCallback } from 'react';
+import type { Node } from 'react';
 import { View } from 'react-native';
 
 import type { RouteProp } from '../react-navigation';
@@ -30,7 +31,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'allStreams', void>,
 |}>;
 
-export default function StreamListCard(props: Props) {
+export default function StreamListCard(props: Props): Node {
   const dispatch = useDispatch();
   const auth = useSelector(getAuth);
   const canCreateStreams = useSelector(getCanCreateStreams);

src/title/ActivityText.js

@@ -1,6 +1,7 @@
 /* @flow strict-local */
 
 import React from 'react';
+import type { Node } from 'react';
 import type { TextStyleProp } from 'react-native/Libraries/StyleSheet/StyleSheet';
 
 import type { UserOrBot } from '../types';
@@ -14,7 +15,7 @@ type Props = $ReadOnly<{|
   user: UserOrBot,
 |}>;
 
-export default function ActivityText(props: Props) {
+export default function ActivityText(props: Props): Node {
   const { style } = props;
   const presence = useSelector(state => getPresence(state)[props.user.email]);
   const userStatus = useSelector(state => getUserStatus(state)[props.user.user_id]);

src/topics/TopicListScreen.js

@@ -1,6 +1,7 @@
 /* @flow strict-local */
 
 import React, { useState, useCallback, useEffect } from 'react';
+import type { Node } from 'react';
 
 import type { RouteProp } from '../react-navigation';
 import type { AppNavigationProp } from '../nav/AppNavigator';
@@ -17,7 +18,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'topic-list', {| streamId: number |}>,
 |}>;
 
-export default function TopicListScreen(props: Props) {
+export default function TopicListScreen(props: Props): Node {
   const dispatch = useDispatch();
   const stream = useSelector(state => getStreamForId(state, props.route.params.streamId));
   const topics = useSelector(state => getTopicsForStream(state, props.route.params.streamId));

src/user-status/UserStatusScreen.js

@@ -1,5 +1,6 @@
 /* @flow strict-local */
 import React, { useState, useContext, useCallback } from 'react';
+import type { Node } from 'react';
 import { FlatList, View } from 'react-native';
 import { TranslationContext } from '../boot/TranslationProvider';
 import { createStyleSheet } from '../styles';
@@ -33,7 +34,7 @@ type Props = $ReadOnly<{|
   route: RouteProp<'user-status', void>,
 |}>;
 
-export default function UserStatusScreen(props: Props) {
+export default function UserStatusScreen(props: Props): Node {
   const dispatch = useDispatch();
   const userStatusText = useSelector(getSelfUserStatusText);