audio: Add a helper class to simplify legacy HALs migration am: 43a85cfb2b am: 24d182487c am: 0b1e574946

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2674340

Change-Id: Ifdfef5c7f205f0c595a6930de979a6ebc0fdd66e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>