Phone refactor

This change is to replace deleteAndCreatePhone() with a simple switch
of RAT in GsmCdmaPhone. It also merges a number of other GSM and
CDMA files (Call, CallTracker, Connection, Phone,
PhoneBookIntefaceManager, CallFailCause), and gets rid of PhoneProxy.

Main pending items:
1. General cleanup of merged code
2. Sanity, regression testing by test team

Bug: 25793157
Change-Id: I08f55b325992fdc0f568d42433507b70b6ceb06d