Implement VirtualAudioDevice API

Add createVirtualAudioDevice() API in VirtualDevice to return a VirtualAudioDevice object for the caller to capture audio and inject microphone to applications running on the specified virtual display.

The VirtualAudioController in service side will responsible for listening virtual display running applications change, playback and recording config change, then notify the VirtualAudioSession to update AudioRecord/AudioTrack inside the AudioCapture/AudioInjection class internally.

Bug: 201558304
CTS-Coverage-Bug: 218528439
Test: atest FrameworksCoreTests:android.companion.virtual, atest FrameworksServicesTests:com.android.server.companion.virtual, manual testing with Exo by ag/16575248
Change-Id: I74f3da67b76aaa909943fbfc8418bf22d637ca39