TelephonyManager Carrier Network Change Notification

Adds a way for a carrier app to notify the system that an intended network
change is starting or ending. This can be used by a system PhoneStateListener
to provide custom UI or perform other actions during this period.

- Adds new public TelephonyManager API: notifyCarrierNetworkChange(boolean)
- Adds new @hide PhoneStateListener method: onCarrierNetworkChange(boolean)
- Functionality merely serves as a pass-through of data from an app to a
  PhoneStateListener (SystemUI for the intended use case)
- Protected by MODIFY_PHONE_STATE permission or hasCarrierPrivileges().

Bug: 11392659

Change-Id: I3199e21ec1ac124198f44b86c1534dd3ff1f6858