4563 [webview_flutter] Implement loadRequest in Android package. (cla: yes, waiting for tree to go green, p: webview_flutter, platform-android)

4569 [webview_flutter] Add a backgroundColor option to the Android webview (cla: yes, p: webview_flutter, platform-android)

4580 Remove deprecated plugins (cla: yes, p: battery, p: android_alarm_manager, p: android_intent, p: image_picker, p: share, p: video_player, p: package_info, p: wifi_info_flutter, p: sensors, p: connectivity, p: device_info, platform-ios, platform-android, platform-macos, platform-web)

4581 [webview_flutter] Android implementation of loadFlutterAsset method. (cla: yes, waiting for tree to go green, p: webview_flutter, platform-android)