4506 Enable camera/quick_actions tests  (cla: yes, waiting for tree to go green)

4507 [url_launcher] Add null check for extracting browser headers (cla: yes, waiting for tree to go green, p: url_launcher, platform-android)

4509 [webview_flutter] Add onUrlChanged callback to platform interface. (cla: yes, waiting for tree to go green, p: webview_flutter)

4512 Add link to CHANGELOG style in PR template (cla: yes, waiting for tree to go green)

4514 Enable Android integration tests in remaining plugins (cla: yes, waiting for tree to go green, p: camera, p: in_app_purchase, p: url_launcher, p: video_player, p: shared_preferences, platform-android)