audio policy: update spatializer policy

Modify the rules to open and close the spatializer output
to address more scenarios:
- more than one spatializer output profile available
- some devices only reachable via a spatializer output profile

The spatializer outputs are opened and closed like other outputs
and a logic evaluates the best output when getSpatializerOutput()
is called

Bug: 188502620
Test: make
Change-Id: Id336e5c38a398525b3fab406cedce8a010d6c854