AudioFlinger: enforce OP_RECORD_AUDIO during recording

  Fix issue where RecordTrack silencing didn't silence the
full buffer: the memset to 0 was using the RecordThread frame
size, not the RecordTrack frame size.
  OP_RECORD_AUDIO was only enforced at the start of a recording
which would fail if not granted. This patch silences the recording
(i.e. silence is recorded instead) when it is lost, and undoes that
when granted again. This requires:
- propagating the package name of the client to the RecordTrack class
- registering an appOp callback in RecordTrack (through a new
  OpRecordAudioMonitor class) to (un)silence the recording
- update the isSilenced() method to take into account the appOp.

Bug: 138968594
Bug: 138636979
Test: run app that records audio, then "adb shell appops __pack_name__ 27 2"
     and verify recording is silent after that.

Change-Id: I4ebdb2f02409fdf045a77132bf7a1b24249ad948
Merged-In: Ib33f5b592185a67204997213bab1ac2594d90d37