Merge sub pages for lock/unlock into 1 xml.

And create PreferenceControllers for each setting

The page is still pretty janky and controllers are invoked manually.
Next CL will clean these up.

Bug: 32953042
Test: TODO
Change-Id: I1d7478324f5de4fdb464d79f89086f7e79c0ee67

src/com/android/settings/widget/MasterSwitchPreference.java

@@ -22,7 +22,6 @@ import android.util.AttributeSet;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Switch;
-import android.widget.TextView;
 
 import com.android.settings.R;
 import com.android.settingslib.RestrictedLockUtils.EnforcedAdmin;