4242 Fix and test for ‘implements’ pubspec entry (cla: yes, p: camera, p: file_selector, p: google_maps_flutter, p: google_sign_in, p: image_picker, p: in_app_purchase, p: url_launcher, p: video_player, p: shared_preferences, p: connectivity, platform-ios, platform-android, platform-macos, platform-web)