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

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

Change-Id: I738766e76dbcb954f346b8f989eba2b7bf330ee8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>