Bug: 22979576 CTS: RingtoneManagerTest failing

Added a utils file to turn on/off appops. Also added
calls to use the utility method to turn on appops for write_settings
for RingtoneManagerTest. This should stop the tests from failing.

Change-Id: I9d787fc7dbb48c95c57d0199a3b6122a488db07f
2 files changed