3556 Publish check (cla: yes)

3557 [url_launcher] Re-endorse null-safe web implementation. (cla: yes, nnbd, p: url_launcher)

3558 [camera] Added timeout to Android pre-capture sequence (cla: yes, p: camera, platform-android)

3559 [path_provider] Migrate examples to null-safety (cla: yes, nnbd, p: path_provider, platform-linux, platform-macos, platform-windows)

3560 Publish check ignores prerelease sdk (cla: yes)

3561 [video_player] Ignore setting mixWithOthers in web (cla: yes, p: video_player, platform-web)

3562 [camera] Solves delay when using the zoom feature on iOS. (cla: yes, p: camera, platform-ios)