Audio HAL: Add support for incall music usecase

This change adds the incall music uplink usecase to the audio hal.
The change adds a check for the AUDIO_OUTPUT_INCALL_MUSIC_UPLINK flag
when opening an output stream. The playback config logic as well as the
mixer path and flag name is the same one
which is used for the usecase in other repo/code paths.
This is part of a larger change which will enable routing audio playback to the
uplink stream using the AudioTrack and setPreferredDevice method, and
will only be available for apps with the MODIFY_PHONE_STATE permission.

Bug: 69973354.
Test: Tested manually.
Change-Id: Ief23049936134b27aefff449c25e8579ce24489e