Check permission for soundtrigger detection service

The app which gets bound to use microphone in the background should be
holding the CAPTURE_AUDIO_HOTWORD permission.

Test: Verify current services still work
      Verify that app without permission can't be registered
Bug: 155438570
Change-Id: I4b53c45bc74df4e91026e13c7e2bfa0f5461df52
1 file changed