Support Call Forwarding and Call Waiting APIs for voice call.

Allows system apps to get/set call forwarding configuration including
 reason, status, number and timeout.

Allows system apps to get/set the status for call waiting function;
Call waiting function enables the waiting for the incoming call when
 it reaches the user who is busy to make another call and allows users
 to decide whether to switch to the incoming call.

Test: Cts; Treehugger; https://paste.googleplex.com/5810435984982016
Bug: 147920077
Change-Id: Iadeea607749c67209df8cb1313f8b134df0a5c4a
Merged-In: Iadeea607749c67209df8cb1313f8b134df0a5c4a
(cherry picked from commit ce96e26c)