Support TYPE_BUS for call audio routing.

This CL adds support for handling TYPE_BUS (auto case) in the audio
routing. This route is used by auto devices where earpiece and speaker
aren't available. The current implementation resolves the routing to
an INVALID type which causes tests to fail as call endpoints aren't
updated accordingly. For now, we can resolve the route to
CallAudioState.ROUTE_SPEAKER as is done in the legacy audio routing in
order to resolve the test failures.

Moving forward, we can rework this if audio fwk team decides to
whitelist TYPE_BUS as a valid communication device. For now, this audio
device doesn't need to use the set/clear communication device APIs.

Bug: 364562758
Test: atest CallAudioRouteControllerTest
Flag: com.android.server.telecom.flags.use_refactored_audio_route_switching
Change-Id: Idf30cfb6b4e65e4add0c5b402211aeb680cda7c9