Don't record audio if UID is idle - media framework

To protect user's privacy if a UID is in an idle state we allow
recording but report silence (all zeros in the byte array) and once
the process goes in an active state we report the real mic data.
This avoids the race between the app being notified aboout its
lifecycle and the audio system being notified about the state
of a UID.

Test: Added - AudioRecordTest#testRecordNoDataForIdleUids
      Passing - cts-tradefed run cts-dev -m CtsMediaTestCases
                    -t android.media.cts.AudioRecordTest

bug:63938985

Change-Id: I1442a9dda1553e9ea7a4a654c50555ac1ec06aa0