AudioRecord: Allow to share capture history.

Add the possibility for privileged applications to
share part of their audio capture history with another app.

A privileged app with permission CAPTURE_AUDIO_HOTWORD can share part of
its recent capture history on a given AudioRecord with the following
steps:
1) Specify the maximum time in the past that will be available for other
apps by calling setMaxSharedAudioHistoryMillis() on the AudioRecord.Builder
when creating the AudioRecord
2) Start recording and determine where the other app should start
capturing in the past.
3) Call AudioRecord.shareAudioHistory() with the package name of the app the history
will be shared with and the intended start time for this app's capture relative to
this AudioRecord's start time.
4) Communicate the MediaSyncEvent returned by shareAudioHistory() to the other app
5) The other app will use the MediaSyncEvent when creating its AudioRecord by calling
setSharedAudioEvent() on the AudioRecord.Builder.
6) Only after the other app has started capturing can this app stop capturing and
release its AudioRecord.

Bug: 183705547
Test: regression on capture use cases

Change-Id: I5beba6c1e489148a14ba86165b8ef2fdc78c802a