AudioService: properties for configuring head tracking default

  Define new property to indicate whether head tracking for spatial
audio is enabled by default.
  Read property in AudioService and pass it to SpatializerHeper
which will use the defalut value every time a new device connects.
  Fix unit test to account for recent hardening of device
compatibility management. Add initialiation test method in
SpatializerHelper to ensure we can test settings with devices
for binaural and transaural modes.

Bug: 242620201
Test: pair BT headset, observe head tracking toggle in UI
Test: atest SpatializerHelper
Change-Id: Ie3af7a13537d114cb603d3c83e9ca2ba86cd7f67