Dynamic audio policies on UID

When looking for an output, take attributes and UID into account.
To find the matching mix: for each mix
- inspect which rules are used
- find a candidate mix for usage
- check UID compatibility
Rename AttributeMatchCriterion to AudioMixMatchCriterion to be consistent
 with the fact that now mixing rules are not always about audio attributes.

Bug 26798796

Change-Id: I1520b0df190a98f197ea8e0144b770e1e6d97888