audio: Add addtl permission sync behavior

The original addition of ther permission sync barrier just synchronized
up to handling permission change events within AudioService itself.

Modify the sysprop listener to be able to handle requests to manually
refresh the sys prop state, and trigger an event if any change occurred.
This entirely eliminates any potential raciness.

Test: atest CtsMediaAudioTestCases
Bug: 338089555
Flag: com.android.media.audio.audioserver_permissions
Change-Id: I357b7b9f36f109426273e8956a77aabfbc2a72f3