Feature/refactor contributions (#3046)

* * Refactored ContributionsListFragment to use RecyclerView
* Added ContributionsPresenter
* Extracted out the cursor to presenter
* Probable fix for #3028

* Improved the logic for cache in ContributionViewHolder

* Some more refactoring

* While displaying images in ContributionsList, check if status is not completed && local uri exists, use that uri to show image

* typo correction in LocalDataSource

* Fixed formatting in ContributionsPresenter

* retain adapter position when orientation changes

* retain child position with its id

* Made ContributionViewHolder not implement ViewHolder

* Code formatting, review suggested changes

* initialise the rv layout managers only when needed

* added test cases for ContributionPresenter

* removed not needed semi colon

* added more java docs and code formatting

app/src/main/java/fr/free/nrw/commons/bookmarks/BookmarksActivity.java

@@ -135,31 +135,4 @@ public class BookmarksActivity extends NavigationBaseActivity
         }
         return adapter.getMediaAdapter().getCount();
     }
-
-    /**
-     * This method is never called but it was in MediaDetailProvider Interface
-     * so it needs to be overrided.
-     */
-    @Override
-    public void notifyDatasetChanged() {
-
-    }
-
-    /**
-     * This method is never called but it was in MediaDetailProvider Interface
-     * so it needs to be overrided.
-     */
-    @Override
-    public void registerDataSetObserver(DataSetObserver observer) {
-
-    }
-
-    /**
-     * This method is never called but it was in MediaDetailProvider Interface
-     * so it needs to be overrided.
-     */
-    @Override
-    public void unregisterDataSetObserver(DataSetObserver observer) {
-
-    }
 }