Release session when apps are terminated

This change releases any sessions and resources associated to apps that
are terminated. This enables the sender to disconnect when the re-routed
(aka mirrored) application is terminated.

Bug: b/362507305
Test: CtsMediaRouterTestCases
Flag: com.android.media.flags.enable_mirroring_in_media_router_2
Change-Id: Ia2cbd5ebf1b869ba61c717bdba3e86125af686ac