25770 Fix crash when FlutterFragmentActivity is recreated with an existing FlutterFragment (platform-android, cla: yes, waiting for tree to go green)

25785 [Engine] Support for Android Fullscreen Modes (platform-ios, platform-android, cla: yes, waiting for tree to go green, platform-fuchsia)

25843 [flutter_releases] Flutter Stable 2.0.6 Engine Cherrypicks (platform-ios, platform-android, cla: yes, platform-web, platform-macos, platform-linux, platform-windows, platform-fuchsia, embedder)

25851 Fix crash when both FlutterFragmentActivity and FlutterFragment are destroyed and recreated (platform-android, cla: yes)

25860 Moved PlatformMessage’s to unique_ptrs (platform-ios, platform-android, cla: yes, waiting for tree to go green, platform-fuchsia, embedder)