Add sound trigger control by audio policy

Audio policy:
- Added active capture indication to sound trigger service:
recognition stops if concurrent capture is not supported.
- Added generation of reserved I/O handle and session ID for
utterance capture.

Sound trigger service
- Added sound model update callback handling.
- Added service state callback
- Simplified callback shared memory allocation.

Bug: 12378680.

Change-Id: Ib0292c2733e6df90fdae480633dd9953d0016ef1