Hide Bluetooth, Reset, Accessibility Settings in ARC

This is an upstreaming change of http://ag/8541963 and
http://ag/10296201 to hide some items from settings search.

This CL also adds javadoc to some settings classes to fix pre-upload
warnings.

Bug: 153704887
Test: Manual. In ARC build, "bluetooth" and "accessibility" no longer shows related settings.
Change-Id: Ic3e9217944251adbea1bdd67baf66d3a9e89583a

src/com/android/settings/accessibility/MagnificationSettingsFragment.java

@@ -40,7 +40,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 
 /** Settings page for magnification. */
-@SearchIndexable
+@SearchIndexable(forTarget = SearchIndexable.ALL & ~SearchIndexable.ARC)
 public class MagnificationSettingsFragment extends DashboardFragment {
 
     private static final String TAG = "MagnificationSettingsFragment";