Support communication device APIs for TYPE_BUS

Audio fwk team has agreed to allow list TYPE_BUS as a valid
communication device. Modify the existing code so that TYPE_BUS uses the
set/clear communication device logic and ensure that retrieval of the
audio route is done via AudioManager#getAvailableCommunicationDevices.

Bug: 365612739
Bug: 367798741
Test: atest CallAudioRouteControllerTest
Test: atest ExtendedInCallServiceTest#testSwitchCallEndpoint
Flag: com.android.server.telecom.flags.use_refactored_audio_route_switching
Change-Id: I920c45e9e22b4489c6cae5d88ff39689be0ab75f