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/fuelgauge/PowerUsageSummary.java

@@ -870,7 +870,7 @@ public class PowerUsageSummary extends PowerUsageBase implements
 
                 @Override
                 public List<String> getNonIndexableKeys(Context context) {
-                    List<String> niks = new ArrayList<>();
+                    List<String> niks = super.getNonIndexableKeys(context);
                     // Duplicates in display
                     niks.add(KEY_AUTO_BRIGHTNESS);
                     niks.add(KEY_SCREEN_TIMEOUT);