Modified to operated when acceptRingingCall or endCall in TelecomManager are...

Modified to operated when acceptRingingCall or endCall in TelecomManager are called with SIMULATED_RING state

After STATE_AUDIO_PROCESSING state is changed to SIMULATED_RING,
when TelecomManager#acceptRingingCall, TelecomManager#endCall are called,
answer & reject would be operated.

Test: Added unit tests
Bug: 151188751

Signed-off-by: Junyeong Bak <junyeong.bak@samsung.com>
Change-Id: I12493b3d5781439bba66c9ecdc5def1a4a358ffa
Merged-In: I12493b3d5781439bba66c9ecdc5def1a4a358ffa