Add searchable metadata attribute for injected tiles.

Allowing the injector to directly control search behavior for their tiles.

Bug: b/299430183
Test: robotest, manual
Change-Id: I21915978d6722998a45741410cca72448aacf2e0

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

@@ -454,7 +454,7 @@ public class SettingsSearchIndexablesProvider extends SearchIndexablesProvider {
             // Skip Settings injected items because they should be indexed in the sub-pages.
             return false;
         }
-        return true;
+        return tile.isSearchable();
     }
 
     private static Object[] createIndexableRawColumnObjects(SearchIndexableRaw raw) {