Plumb SuggestionControllerMixin to DismissController.

- The SuggestionControllerMixin is needed to dismiss a suggestion.
- When swipe a suggestion, SuggestionControllerMixin is called, which
  then calls API in SuggestionService to dismiss a suggestion.

Bug: 65065268
Test: robotests
Change-Id: I6a0c5823d60b995ab4a36b1c91777f5cd31a500d

src/com/android/settings/dashboard/suggestions/SuggestionControllerMixin.java

@@ -111,4 +111,8 @@ public class SuggestionControllerMixin implements SuggestionController.ServiceCo
     public void onLoaderReset(Loader<List<Suggestion>> loader) {
 
     }
+
+    public void dismissSuggestion(Suggestion suggestion) {
+        mSuggestionController.dismissSuggestions(suggestion);
+    }
 }