Add facade APIs for HFP service required for topshim testing.

Bug: 250899887
Test: mma -j $(nproc)
Test: ./build.py
Test: system/gd/cert/run --clean --topshim
Tag: #floss
Change-Id: Ib050a2e6b005ab0ad21cf9cb3def563597bdded9

Change-Id: I8b5395b2ee351aab1519acbabbba2e8372923f6a