Send audio-presentation metadata in access units

Audio presentation metadata is attached to the access units so that
each media buffer read() retreives it's associated audio
presentations information.

Bug: 120846068
Test: atest CtsMediaTestCases:MediaExtractorTest#testGetAudioPresentations
      repeat 3..5 times
Change-Id: I47f4d0dd959537fe98aa757bfa762ff02aa86a35