Add support for handling microphone disable by multiple users

Support handling the microphone toggle setting for multiple
foreground users, with possible dissimilar setting states.

Test: On a device with a guest user added by the owner in the system
settings UI (assume starting with the owner profile):
- Build CHRE with the audioworld static nanoapp to constantly request
audio data, load to device and reload CHRE.
- Enable the microphone privacy setting for the owner via the adb CLI,
verify that audio world is not getting data, and that the audio source
has been suspended.
- Switch to the guest user via the system UI, observe that the
audioworld nanoapp is now receiving data.
- Reset to initial state, repeat while starting from the guest profile
for a quick consistency check.

Bug: 174691697
Change-Id: If92170c82363356fcbb1ddc2abdcd25a5ed85039