Floss: Migrate QALegacy methods to QA

This moves all QALegacy methods to QA interface. Since QA interface is a
thin layer that just conveys commands to a struct via message system,
some results can't be returned on time. Therefore, we return the result
in a corresponding callback.

Bug: 261143122
Test: run btclient adapter show

Change-Id: Ibe012e00df010ffa38ce15121f83957620b4271f