floss: supports local name in advertising data

We keep a pointer to the Bluetooth adapter in BluetoothGatt context,
and use it to get the adapter name while starting an advertising set.
If the a local name field is required in this advertising set,
the adapter name will be converted to either completed local name or
shortened local name field, and then appended to the advertising data.

Bug: 233128394
Tag: #floss
Test: ./buid.py --target test
Test: "adapter set-name xyz "and "advertise on" on btclient

Change-Id: I01295188dc607f22fd78229feafd070982a2ed2f