3555 [in_app_purchase]  Migrate to NNBD (cla: yes, nnbd, p: in_app_purchase, platform-ios)

3562 [camera] Solves delay when using the zoom feature on iOS. (cla: yes, p: camera, platform-ios)

3591 [camera] Fix iOS rotation issue (cla: yes, p: camera, platform-ios, waiting for tree to go green)

3616 [ios_platform_images] Bump version for stable NNBD (cla: yes, nnbd, p: ios_platform_images, platform-ios, waiting for tree to go green)

3621 [quick_action] fix delegate methods not called on iOS (cla: yes, p: quick_actions, platform-ios, waiting for tree to go green)