Floss: GATT facade service and client topshim test apis.

Bug: 233128294
Bug: 193686696
Bug: 193686094
Bug: 234029443
Test: mma -j $(nproc)
Test: ./build.py
Test: system/gd/cert/run --clean --topshim
Tag: #floss
Change-Id: Ida4a62f8132e3cf98ca08a77ee5992c6f3522ff1