Add android.media.audio.common.AidlConversion class

This class is intended to host conversion functions
between the types from AIDL android.media.audio.common
packages and SDK Java API types, as well as legacy
system/audio.h (native) types.

Move existing conversion functions from Soundtrigger's
utility functions to AidlConversion.

Bug: 188932434
Test: atest SoundHw2CompatTest
Change-Id: I3041fce921112c06fb001638e35b26abb3fd0c72