Misc fixes to search and UI.

- Use prefContext to create preference.
- rename "Gestures" to "Gesture shortcuts"
- Add search keyword to individual gesture settings so when search
  "gesture" they also show up.
- call super() for all getNonIndexableKeys() in search provider

Fix: 38327387
Fix: 36621897
Fix: 36685646
Test: make RunSettingsRoboTests

Change-Id: Ia5ddfeae08cb27c278dfb8d2376594e21d8f283c

src/com/android/settings/network/NetworkDashboardFragment.java

@@ -207,7 +207,7 @@ public class NetworkDashboardFragment extends DashboardFragment implements
 
                 @Override
                 public List<String> getNonIndexableKeys(Context context) {
-                    List<String> keys = new ArrayList<>();
+                    List<String> keys = super.getNonIndexableKeys(context);
                     // Remove master switch as a result
                     keys.add(WifiMasterSwitchPreferenceController.KEY_TOGGLE_WIFI);
                     return keys;