Dynamic audio policies: multi-zone through uid/device affinity

Augment dynamic audio policies with audio device affinity for
 apps (a.k.a multi-zone handling), to enable associating apps
 with a set of audio devices (which may form a "zone" in cars).

Bug: 111647296
Test: requires device with routing policy started by CarService
Change-Id: I2994ae80624556d9321f788a0575d9f732157228