Introduce support for notifying specific media projection events to enable...

Introduce support for notifying specific media projection events to enable handling of projections post-call end

Bug: 390343524
Test: atest MediaProjectionStopControllerTest
Flag: com.android.media.projection.flags.show_stop_dialog_post_call_end
Design Doc: go/dd-stop-dialog-on-call-end

Change-Id: Iad8f1f075631ae05057e211ef49e62d27cb96fe1