1713 [firebase_ml_vision] Prepare example app to include Live Camera Preview demo and Material Barcode Scanner demo (cla: yes)

1714 [quick_actions] Update README.md (cla: yes)

1720 [cloud_firestore] Fix document pagination (cla: yes)

1722 [cloud_firestore] Added support for combining document pagination methods (cla: yes)

1724 Add a note about mockito to contribution guide (cla: yes)

1725 [all_plugins] Build all_plugins app on cirrus script (cla: yes)

1728 [firebase_messaging]: add additional documentation for the data in notifications (cla: no, flutterfire, submit queue)

1729 Fix build failures due to CocoaPods version (cla: yes)