4076 Update cirrus gcp credentials (cla: yes)

4077 [in_app_purchase] billingClient launchPriceChangeConfirmationFlow (cla: yes, waiting for tree to go green, p: in_app_purchase, platform-android)

4079 [in_app_purchase] update gradle tool to 4.1.0 (cla: yes, p: in_app_purchase, platform-android)

4081 [video player]: update the url in the readme example (cla: yes, waiting for tree to go green, p: video_player)

4083 [image_picker_for_web] Migrate image_picker to package:cross_file (cla: yes, p: image_picker, platform-web)

4084 [flutter_plugin_tools] Migrate analyze to new base command (cla: yes)