Listen to capability discovery settings in the registry

When the user changes their capability discovery settings
make the TelecomAccountRegistry aware of this immediately instead of
waiting for the PhoneAccount to be recreated another way.

Bug: 150894805
Test: manual, verify capability discovery is enabled/disabled correctly.
Change-Id: I20110b5d5260d41ef609974d2d66d54d60626782
1 file changed