APM: support querying of audio playback routing

  Add support for querying the audio devices used for playback
routing for the given audio attributes.
  Take into account registered dynamic policies but disregard
secondary output descriptors as they are used for playback
capture.

Bug: 144440677
Test: atest AudioServiceHostTest
Change-Id: I102c57b432b044dc6b0ead49e0a30d8e9094411d