sendDialerCode API review

address the feeback from API review:
throw exception rather than a boolean return.
handle exception from callers instead of check return boolean
move secret code detection logic from API to API callers.

Bug: 35767402
Test: Manual
Test: run cts -m CtsTelephonyTestCases -t android.telephony.cts.TelephonyManagerTest
Change-Id: Ie31f399799d4cd2413bf65a227fb000bbbe3c8aa
2 files changed