Feature/manga migration (#536)

* Add "migration" tab to "Browse" screen

* Add missing useEffect cleanup for navbar title and actions

* Make "SourceGridLayout" reusable

* Add migration tab to "Browse"

* Add migration logic

src/screens/DownloadQueue.tsx

@@ -142,6 +142,11 @@ export const DownloadQueue: React.FC = () => {
                 </Tooltip>
             </>,
         );
+
+        return () => {
+            setTitle('');
+            setAction(null);
+        };
     }, [t, status, isQueueEmpty]);
 
     useEffect(() => {