- Move preference related logic to controllers.
- Add some test cases for controllers.
Test: manual
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.nfc
make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.core
atest SettingsGatewayTest UniquePreferenceTest
Change-Id: I061a194c170f63fab51974f26c24be43d67d6f6f