Enforce basic thread safety in Audio Policy Service

Enable clang thread safety analysis. Convert comments on TS
into directives. Fix missing lock acquisitions. Add missing
default initializers for the fields of UidPolicy and
SensorPrivacyPolicy

Also remove unused fields mpAudioPolicyDev and mpAudioPolicy
from AudioPolicyService.

TODO: Consider protecting pointers to command threads,
APM instance and the client, and system usages with a separate
lock.

Bug: 70398235
Bug: 155336464
Test: make, flash, and test audio on device
      execute "adb shell cmd media.audio_policy" commands
Change-Id: I47b132c8b5c977812fad5c89fa57882a37779c18
Merged-In: I47b132c8b5c977812fad5c89fa57882a37779c18