Fix bug #15460001 "Cell broadcasts" setting search suggested in wifi only device though setting is not present

- implement a BaseSearchIndexProvider for WirelessSettings
- fix Context passed to the Index: now use an ApplicationContext
- also use the correct Context when dealing with Settings SearchIndexProvider
- also makes impossible a rogue BaseSearchIndexProvider to crash Settings
if not well behaving
- last, fix icon used for "NFC & more" search results

Change-Id: I8b5cc999fa57a9e1977ee57394801d54cf3dbabb

src/com/android/settings/search/SearchIndexableResources.java

@@ -87,9 +87,9 @@ public final class SearchIndexableResources {
         sResMap.put(WirelessSettings.class.getName(),
                 new SearchIndexableResource(
                         Ranking.getRankForClassName(WirelessSettings.class.getName()),
-                        R.xml.wireless_settings,
+                        NO_DATA_RES_ID,
                         WirelessSettings.class.getName(),
-                        R.drawable.empty_icon));
+                        R.drawable.ic_settings_more));
 
         sResMap.put(HomeSettings.class.getName(),
                 new SearchIndexableResource(