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/settings/Backup.tsx

@@ -62,6 +62,11 @@ export function Backup() {
     useEffect(() => {
         setTitle(t('settings.backup.title'));
         setAction(null);
+
+        return () => {
+            setTitle('');
+            setAction(null);
+        };
     }, [t]);
 
     useSetDefaultBackTo('settings');