Check WiFi call setting

This CL does the following:
  - checks the WiFi call setting when placing calls
  - if the WiFi call setting is ASK_EVERY_TIME then displays a dialog
    asking the user to choose
  - changes the default WiFi call setting to always use WiFi calling
  - set Call.isWifiCall when using Wifi calling

Change-Id: I9dc6086c41d4fe1b2a693ff44b5266697eae0f89
7 files changed