[DO NOT MERGE] Keep track of audio recordings that are silenced

Sometimes, an app will have an active App Op for recording, but it is
silenced (for example, after a while being in background). This means
they cannot get the recording audio stream.

This change keeps track of that and prevents them from being considered
as actively using AppOpsManager.OP_RECORD_AUDIO from SystemUI's
perspective. It does two things:

- If a particular UID has any of its AudioRecordingConfigurations as
silenced, it will be marked as paused and an inactive update will be
sent to listeners of AppOpsController. When the recording stops being
silent, an active update will be sent.
- When getting the list of active items, paused ones will be filtered
out.

Test: manual with recording app
Test: atest AppOpsControllerTest
Bug: 162552566
Change-Id: I72fbebf4b37b799907855d57e6c615c244b63999