base

Implement MHL send key action.

This class introduces two classes, MhlSendKeyAction and
HdmiMhlKeycode.
 - MhlSendKeyAction is a feature action that manages MHL message
for RCP, Remote Control Pass Through.
 - HdmiMhlKeycode is a collection of MHL keycode including keycode
mapping between MHL and Android keycode.

Bug: 16966459
Change-Id: Ib3f7229c71b66837cd0d239e5af1940dfccee7df