SmsSenderCallback: Run the callback with the phone UID.

The SmsSenderCallback needs to run as the phone UID because of checks that
ensure only the messaging app or phone process can run that code.

Also modifies SmsUsageMonitor to allow phone process to make calls.

Bug: 19302541
Change-Id: Ic6b8141fbf15f42696e9b86d3c599ef2ec4ebd1c