configs: add car audio configuration for multi-zone support

Add car audio configuration xml file including
    - Audio zones
    - Display to audio zone mappings
    - Context to audio bus mappings
    - Volume groups
Deprecate car volume groups overlay file.
Add rear seat zone as secondary zone in audio policy
configuration.

Change-Id: Ie7b8b1e6ee16b0cef8bdb48afed43faa729591f8