[google_sign_in_platform_interface] Add missing docs (flutter#2359)

[connectivity] Adds Macos support (flutter#2306)

[video_player] Document public API of video_player_platform_interface. (

flutter#2355)

[video_player_platform_interface] Fix some pedantic lints (flutter#2349)

Fixes unawaited_futures. There are still some undocumented members here
that are unclear to me, so unfortunately the analysis_options.yaml is
still there.

[ android_alarm_manager ] Loosen Flutter SDK lower bound, update READ…

…ME (flutter#2338)

[video_player] Add web implementation using platform interface (flutt…

…er#2279)

* Add web implementation

* Address review comments

* Rename setupVideoPlayer() to initialize()

* Send correct VideoEventType

* Add autoplay note to README.

[webview_flutter] Fix pedantic lint errors (flutter#2322)

[video_player] Fix pedantic lints (flutter#2321)

Fix pedantic lints. This fixes some potential race conditions in cases where
futures within some video_player methods weren't being awaited correctly.

[share] Fix pedantic lints (flutter#2320)

[package_info] Fix pedantic lints (flutter#2319)

This involved internally refactoring how the `PackageInfo.fromPlatform`
code handled futures, but shouldn't change existing functionality.