audio HAL: Initial AIDL interfaces

This adds basic support for enumerating capabilities
of an audio module, creation of patches, and opening of
I/O streams.

Bug: 205884982
Test: atest VtsHalAudioCoreTargetTest
Merged-In: Ib1ef13c95d338b6ef1bde7d87dcd675fc1d35e85
Change-Id: Ib1ef13c95d338b6ef1bde7d87dcd675fc1d35e85
(cherry picked from commit ee274782)