Quality of Service API extension - RPC & Driver support

Change-Id: I1a259aac25377d80a3b0b87547be270b43bb1af8
Ml2 QoS API extension support

Implements blueprint ml2-qos

Change-Id: I9316632fbc9080d77fe5faa52d3f00c7cb78c134
Co-Authored-By: Anthony Veiga <Anthony_Veiga@cable.comcast.com>