Add Settings support for Bluetooth Multi-A2DP and Multi-HFP

Test: Code compilation
Bug: 64767509

[NOTE: The cherry-pick removed changes to non-existent code and log
message description that doesn't apply here.]

Change-Id: Iee76286110ed87703d6a968f50273c22cd7c7086
Merged-In: Iee76286110ed87703d6a968f50273c22cd7c7086
(cherry picked from commit 4b796e5d)