Spatializer: Cumulative headtracking fixes

Add thread name for proper debugging.
Raise headtracking event thread priority from normal to highest non-realtime.
Raise spatializer looper thread priority from audio to highest non-realtime.
Prevent logspam on error.
Add sensor start / stop logging.

Test: Validate HT works
Bug: 258737281
Change-Id: Idd80929c43a06eaf6480b569384245b8f66f806f