[Flow202][native][skip-ci] [30/x] Type PushHandler.iosBackgroundNotificationReceived
Summary:
Separating this out because it requires exporting a type.
NOTE: CI will fail on this diff. I considered the possibility of fixing Flow errors BEFORE upgrading Flow, but it wasn't possible... in some cases, the fixes to support the new version of Flow caused errors in the old version. I could have hidden these type errors with $FlowFixMe lines and then later revert those, but that seemed like too much busy work.
Depends on D10013
Test Plan: Confirm the Flow errors go away
Reviewers: marcin
Reviewed By: marcin
Subscribers: tomek
Differential Revision: https://phab.comm.dev/D10014