Telephony: STK CC feature implementation

Add strings and constants required for stk cc feature.

Change-Id: Id5ec987cdc8dc2d9eebdf01fe546eb96ec0c69f9
(cherry picked from commit 0647546)
(cherry picked from commit 17e39ec)

Conflicts:

telephony/java/com/android/internal/telephony/RILConstants.java