UIApplicationDelegate subclass for simple apps that want default behavior.
This class implements the following behaviors:
- Status bar touches are forwarded to the key window’s root view
FlutterViewController, in order to trigger scroll to top.
- Keeps the Flutter connection open in debug mode when the phone screen locks.
App delegates for Flutter applications are not required to inherit from this class. Developers of custom app delegate classes should copy and paste code as necessary from FlutterAppDelegate.mm.