[video_player_platform_interface] messages.dart use 2.12

[flutter_plugin_android_lifecycle] null safety

[connectivity_macos] null safety

[camera] Suppress unchecked cast warning in java test (flutter#3316)

* Suppress unchecked cast warning in java test

* Bumped version number

[camera] Suppress unchecked cast warning in java test (flutter#3316)

* Suppress unchecked cast warning in java test

* Bumped version number

[camera] Add `camera_platform_interface` package (flutter#3253)

* Make sure only camera_platform_interface has updates

* add dev dependency to async package

* refactored import to package import

* Fix formatting issues

[camera] Support Android 30 (flutter#3299)

[video_player] Fix mistake

[file_selector_platform_interface] Migrate to cross_file package (flu…

…tter#3286)

[file_selector] Initial implementation (flutter#3140)

Co-authored-by: Jason Panelli <[email protected]>