flowconfig: HMRLoadingView ignore; better mimic FB internal .flowconfig.

Part of the RN v0.59.10 -> v0.60.0 upgrade [1]. This commit has no
hard constraints on its position relative to the others in the
series, but at least one change (the `HMRLoadingView.js` ignore) is
not necessary until the upgrade.

Corresponds to facebook/react-native@0f909e331.

Leave in one inexplicable line that reveals huge numbers of errors
if removed, mostly in node_modules/react-native/Libraries (but some
in our code as well, e.g., `deprecated-utility` on the use of
`$Subtype` in `redux-persist/index.js.flow`.

```diff
- module.file_ext=.js
- module.file_ext=.jsx
- module.file_ext=.json
- module.file_ext=.native.js
  module.file_ext=.ios.js // This line
```

It's not there in the RN v0.60.0 template, but it's been in our repo
since e38869a, the upgrade from RN 0.51.0 to 0.52.0.

It doesn't seem to have ever been in the template app. The upgrade
helper showing the `rn-diff-purge` diff from RN 0.51.0 to 0.52.0 [1]
doesn't suggest adding that line, but I don't think that tool was
around when that other upgrade was done. Perhaps it was added from
experimentation, or there was another guide to upgrading.

Anyway, there's an open Flow issue [2], which was open at the time
of e38869a, one resolution of which is to include the line that
was included. So, keep including it.

[1]: https://react-native-community.github.io/upgrade-helper/?from=0.51.0&to=0.52.0

[2]: facebook/flow#945

.flowconfig

@@ -8,13 +8,17 @@
 ; Ignore duplicate module providers
 ; For RN Apps installed via npm, "Libraries" folder is inside
 ; "node_modules/react-native" but in the source repo it is in the root
-.*/Libraries/react-native/React.js
+node_modules/react-native/Libraries/react-native/React.js
 
 ; Ignore polyfills
-.*/Libraries/polyfills/.*
+node_modules/react-native/Libraries/polyfills/.*
 
-; Ignore metro
-.*/node_modules/metro/.*
+; These should not be required directly
+; require from fbjs/lib instead: require('fbjs/lib/warning')
+node_modules/warning/.*
+
+; Flow doesn't support platforms
+.*/Libraries/Utilities/HMRLoadingView.js
 
 ; Custom ignores
 .*/ios/Pods/*
@@ -28,6 +32,8 @@
 .*/node_modules/flow-coverage-report/.*
 .*/node_modules/@snyk/.*
 
+[untyped]
+.*/node_modules/@react-native-community/cli/.*/.*
 
 [include]
 ; Effectively this line warns Flow that this path might be a symlink
@@ -51,18 +57,32 @@ flow-typed/@react-native-community/async-storage_v1.x.x.js
 [strict]
 ; These apply only to files where `@flow strict` is enabled.
 ; See https://flow.org/en/docs/strict/ .
+
+; from RN
+deprecated-type
 nonstrict-import
+sketchy-null
 unclear-type
 unsafe-getters-setters
 untyped-import
 untyped-type-import
-sketchy-null
-
 
 [lints]
+; from RN
+sketchy-null-number=warn
+sketchy-null-mixed=warn
+untyped-type-import=warn
+nonstrict-import=warn
+deprecated-type=warn
+unsafe-getters-setters=warn
+inexact-spread=warn
+unnecessary-invariant=warn
+signature-verification-failure=warn
+deprecated-utility=error
+
+; ours
 sketchy-number=error
 unnecessary-optional-chain=warn
-unnecessary-invariant=warn
 
 
 [options]
@@ -86,8 +106,11 @@ module.system.haste.name_reducers='^\(.*\)\.android$' -> '\1'
 module.system.haste.name_reducers='^\(.*\)\.native$' -> '\1'
 module.system.haste.paths.blacklist=.*/__tests__/.*
 module.system.haste.paths.blacklist=.*/__mocks__/.*
-module.system.haste.paths.blacklist=<PROJECT_ROOT>/node_modules/react-native/Libraries/Animated/src/polyfills/.*
 module.system.haste.paths.whitelist=<PROJECT_ROOT>/node_modules/react-native/Libraries/.*
+module.system.haste.paths.whitelist=<PROJECT_ROOT>/node_modules/react-native/RNTester/.*
+module.system.haste.paths.whitelist=<PROJECT_ROOT>/node_modules/react-native/IntegrationTests/.*
+module.system.haste.paths.blacklist=<PROJECT_ROOT>/node_modules/react-native/Libraries/react-native/react-native-implementation.js
+module.system.haste.paths.blacklist=<PROJECT_ROOT>/node_modules/react-native/Libraries/Animated/src/polyfills/.*
 
 munge_underscores=true
 
@@ -98,14 +121,10 @@ suppress_type=$FlowFixMe
 suppress_type=$FlowFixMeProps
 suppress_type=$FlowFixMeState
 
-module.file_ext=.js
-module.file_ext=.jsx
-module.file_ext=.json
-module.file_ext=.native.js
 module.file_ext=.ios.js
 
-suppress_comment=\\(.\\|\n\\)*\\$FlowFixMe\\($\\|[^(]\\|(\\(<VERSION>\\)? *\\(site=[a-z,_]*react_native[a-z,_]*\\)?)\\)
-suppress_comment=\\(.\\|\n\\)*\\$FlowIssue\\((\\(<VERSION>\\)? *\\(site=[a-z,_]*react_native[a-z,_]*\\)?)\\)?:? #[0-9]+
+suppress_comment=\\(.\\|\n\\)*\\$FlowFixMe\\($\\|[^(]\\|(\\(<VERSION>\\)? *\\(site=[a-z,_]*react_native\\(_ios\\)?_\\(oss\\|fb\\)[a-z,_]*\\)?)\\)
+suppress_comment=\\(.\\|\n\\)*\\$FlowIssue\\((\\(<VERSION>\\)? *\\(site=[a-z,_]*react_native\\(_ios\\)?_\\(oss\\|fb\\)[a-z,_]*\\)?)\\)?:? #[0-9]+
 suppress_comment=\\(.\\|\n\\)*\\$FlowFixedInNextDeploy
 suppress_comment=\\(.\\|\n\\)*\\$FlowExpectedError
 suppress_comment=\\(.\\|\n\\)*\\$FlowMigrationFudge