audio: grant focus to qchat application

To achieve QCHAT concurrencies with telephonoy and music player,
QCHAT application should be allowed to run while voice call is
in HOLD/INACTIVE state. Music player should not be granted audio
focus if QCHAT is running.
Add call state, vsid and all_call_states keys so that application
can set/get keyvalues.

Change-Id: Ia8941bf45074dd4edaa9dc236649293496c76e7b