Call waiting support USSD function

-Add new carrier config KEY_USE_CALL_WAITING_USSD_BOOL
Bug: 180540626
Test: build pass. Manual test: set/get call waiting.

Change-Id: I607da1f7c4748303c848f755e668854307c53d15
Merged-In: I607da1f7c4748303c848f755e668854307c53d15
1 file changed