Associate port id to piid in audio service

The implementation reuses the playerEvent callback in the
PlaybackActivityMonitor to track events when the portId changes.

This can be used to track changes that happen on the lower levels to a
track with a given port id and reflect them through the playback
notification API.

Test: make
Bug: 235521198
Change-Id: I5cdf4f47cacc31b2aecffa3029081b01a9e367fd