Clear up bit mask usage in audio policy.

This change includes:
1. Use DeviceTypeSet to represent a combination of audio device types.
2. Add helper functions for DeviceTypeSet
3. Stop using audio device type as a bit mask in DeviceVector

Test: atest AudioTrackTest AudioRecordTest AudioPlaybackCaptureTest
Test: atest AudioHostTest AudioServiceHostTest audiopolicy_tests
Test: audio smoke test
Change-Id: If80513b689848bcab6094f70a572f053856afa82
Merged-In: If80513b689848bcab6094f70a572f053856afa82