Add secondary output to audio tracks

The secondary are returned from mixes (from DAP loopback&render),
from getOutputForAttr.
All getOutputForAttr* of the stack are update.
Internal getOutputForAttr use descriptor, external one use handles.

The secondary output are saved in each track and the track is
invalidated if the list of secondary output changes.

In audio flinger, create a pair of recordTrack & patchTrack to pipe
the intercepted audio audio to the secondary output.

Test: adb shell audiorecorder --target /data/file.raw
Bug: 111453086
Change-Id: Id6523d9e383c15a0e39313d5f355df809b7e72fe