4200 Adds test harnesses for integration tests on Android (cla: yes, waiting for tree to go green, p: google_maps_flutter, p: google_sign_in, p: image_picker, p: quick_actions, platform-android)

4201 [in_app_purchase] Correct mistake with markdown in README.md (cla: yes, waiting for tree to go green, p: in_app_purchase, platform-android)

4202 Correct mistake with markdown in README.md (cla: yes, waiting for tree to go green, p: in_app_purchase, platform-ios)

4203 [camera_web] Add dispose implementation (cla: yes, waiting for tree to go green, p: camera, platform-web)

4207 [camera_web] Add camera errors handling (cla: yes, waiting for tree to go green, p: camera, platform-web)