[image_picker_ios] Update image picker UI test query for iOS 18 (flutter#7325)

The image picker UI changed from iOS 17 -> iOS 18 (beta), and there's an additional scrollview that wasn't present before.
Instead of selecting the first image in the first scroll view, instead select the image with the accessibility label that starts with "Photo":
```
      ��Find: First Match
        Output: {
          Image, 0x10134f070, {{-0.0, 339.7}, {142.2, 142.3}}, label: 'Photo, March 30, 2018, 12:14�PM'
        }
```
This works on previous versions of iOS as well.

Fixes flutter#150220, found in Xcode 16 beta.

Author: jmagman

packages/image_picker/image_picker_ios/CHANGELOG.md

@@ -1,3 +1,7 @@
+## NEXT
+
+* Updates UI test photo element query for iOS 18.
+
 ## 0.8.12
 
 * Re-adds Swift Package Manager compatibility.

packages/image_picker/image_picker_ios/example/ios/RunnerUITests/ImagePickerFromGalleryUITests.m

@@ -201,7 +201,8 @@ - (void)launchPickerAndPickWithMaxWidth:(NSNumber *)maxWidth
   // Find an image and tap on it. (IOS 14 UI, images are showing directly)
   XCUIElement *aImage;
   if (@available(iOS 14, *)) {
-    aImage = [self.app.scrollViews.firstMatch.images elementBoundByIndex:1];
+    NSPredicate *imagePredicate = [NSPredicate predicateWithFormat:@"label BEGINSWITH 'Photo, '"];
+    aImage = [self.app.images matchingPredicate:imagePredicate].firstMatch;
   } else {
     XCUIElement *allPhotosCell = self.app.cells[@"All Photos"].firstMatch;
     if (![allPhotosCell waitForExistenceWithTimeout:kElementWaitingTime]) {

packages/image_picker/image_picker_ios/example/ios/RunnerUITests/ImagePickerFromLimitedGalleryUITests.m

@@ -107,7 +107,9 @@ - (void)testSelectingFromGallery API_AVAILABLE(ios(14)) {
   [self handlePermissionInterruption];
 
   // Find an image and tap on it.
-  XCUIElement *aImage = [self.app.scrollViews.firstMatch.images elementBoundByIndex:1];
+  NSPredicate *imagePredicate = [NSPredicate predicateWithFormat:@"label BEGINSWITH 'Photo, '"];
+  XCUIElementQuery *imageQuery = [self.app.images matchingPredicate:imagePredicate];
+  XCUIElement *aImage = imageQuery.firstMatch;
   os_log_error(OS_LOG_DEFAULT, "description before picking image %@", self.app.debugDescription);
   if (![aImage waitForExistenceWithTimeout:kLimitedElementWaitingTime]) {
     os_log_error(OS_LOG_DEFAULT, "%@", self.app.debugDescription);
@@ -126,7 +128,7 @@ - (void)testSelectingFromGallery API_AVAILABLE(ios(14)) {
   [doneButton tap];
 
   // Find an image and tap on it to have access to selected photos.
-  aImage = [self.app.scrollViews.firstMatch.images elementBoundByIndex:1];
+  aImage = imageQuery.firstMatch;
 
   os_log_error(OS_LOG_DEFAULT, "description before picking image %@", self.app.debugDescription);
   if (![aImage waitForExistenceWithTimeout:kLimitedElementWaitingTime]) {