[infra_ui][overlay] Change insert overlay method parameters to optional

app_flowy/packages/flowy_infra_ui/example/lib/overlay/overlay_screen.dart

@@ -49,6 +49,7 @@ class OverlayScreen extends StatelessWidget {
                     size: 200,
                   ),
                   'overlay_flutter_logo',
+                  null,
                 );
               },
               child: const Text('Show Overlay'),

app_flowy/packages/flowy_infra_ui/lib/src/flowy_overlay/flowy_overlay.dart

@@ -110,7 +110,11 @@ class FlowyOverlay extends StatefulWidget {
 class FlowyOverlayState extends State<FlowyOverlay> {
   List<Tuple3<Widget, String, FlowyOverlayDelegate?>> _overlayList = [];
 
-  void insert(Widget widget, String identifier, FlowyOverlayDelegate? delegate) {
+  void insert({
+    required Widget widget,
+    required String identifier,
+    FlowyOverlayDelegate? delegate,
+  }) {
     setState(() {
       _overlayList.add(Tuple3(widget, identifier, delegate));
     });