Dependency injection of STHAL compatibility

Providing the middleware implementation with the canonical driver (the
one that abstracts away which specific underlying version is used)
allows us to test the middlware implementation and the driver compat
layer in isolation from each other, making the tests simpler and
increasing coverage.

Test: atest SoundTriggerMiddlewareImplTest SoundHw2CompatTest
Change-Id: I978b151d9111c4e007dcfdd4cc5df35d46249615