4186 [camera_web] Add initializeCamera implementation (cla: yes, waiting for tree to go green, p: camera, platform-web)

4187 [webview_flutter] Better documentation of Android Platform Views modes (cla: yes, waiting for tree to go green, p: webview_flutter)

4189 Remove remaining V1 embedding references (cla: yes, p: battery, p: package_info, platform-android)

4190 [camera_web] Add buildPreview implementation (cla: yes, waiting for tree to go green, p: camera, platform-web)

4191 [camera_platform_interface] Expand camera platform interface to support pausing the camera preview. (cla: yes, waiting for tree to go green, p: camera)

4193 Move unit tests to Android modules (cla: yes, p: google_maps_flutter, p: google_sign_in, p: image_picker, platform-android)