Spatializer: add several methods to ISpatializer

Add sevreal methods to Ispatializer interface:
- setParameter() and getParameter() for vendor specific configuration
by engine implementor.
- getOutput() method to query on which output stream
the spatializer is attached to.
- isHeadTrackingSupported() to query if the engine supports head tracking.

Bug: 188502620
Test: make
Change-Id: Ifbded2cf17a45f40d5b6407b8afb4c68c0718ecf