3543 [plugin_platform_interface] Migrate  to v2 stable, null-safe (cla: yes, nnbd, p: plugin_platform_interface)

3544 Move plugin tools code (cla: yes)

3545 Honor, and scrub, the 1.0 compatibility promise (cla: yes, p: android_intent, p: connectivity, p: device_info, p: package_info, p: path_provider, p: sensors, p: share, p: shared_preferences, p: url_launcher, p: video_player, platform-linux, platform-macos, platform-web, platform-windows)

3546 [video_player] Update video_player readme to change sample video to https (cla: yes, documentation, p: video_player)

3547 [google_maps_flutter] Fix CameraPosition regression (cla: yes, p: google_maps_flutter)