Dynamically check for permission denials

Don't crash when performing certain operations that the
dialer might not have permissions to execute:

* Access voicemail provider
* Certain TelecomManager methods

Add a class TelecomUtil that checks for permissions/default
dialer status, and handles the privileged operations
appropriately.

Bug: 20266292

Change-Id: Ibe8a85440b9ca20169b5ce3be24d1a385caaebb6