This change selects the best suited media button receiver
component and pending intent when creating the legacy
session. This is important to ensure that a service can
be started with a media button event from BT headsets
after the app has been terminated.
The `MediaSessionLegacyStub` selects the best suited
receiver to be passed to the `MediaSessionCompat`
constructor.
1. When the app has declared a broadcast receiver for
`ACTION_MEDIA_BUTTON` in the manifest, this broadcast
receiver is used.
2. When the session is housed in a service, the service
component is used as a fallback.
3. As a last resort a receiver is created at runtime.
When the `MediaSessionLegacyStub` is released, the media
button receiver is removed unless the app has provided a
media button receiver in the manifest. In this case we
assume the app supports resuming when the BT play intent
arrives at `MediaSessionService.onStartCommand`.
Issue: androidx/media#167
Issue: androidx/media#27
Issue: androidx/media#314
PiperOrigin-RevId: 523638051
(cherry picked from commit e54a9343)
