Add DISALLOW_DATA_ROAMING restriction support to settings

Added RestrictedSwitchPreference to generalize device admin restriction
support for Telephony. Implemented handling of DISALLOW_DATA_ROAMING
restriction using this.

Bug: 24890464
Change-Id: Ice1fb169527c7612be732719523252f773283961

https://screenshot.googleplex.com/u76rW3HK4Jr
https://screenshot.googleplex.com/xqKUwVofyFB
5 files changed