Bind form widget to controller when duplicating page.

This fixes the modified page counter not working when updating a duplicated page, because the hidden inputs were not in the expected location.

controllers/Index.php

@@ -311,6 +311,8 @@ public function onDuplicateObject(): array
         $duplicatedObject = new $className($data);
 
         $widget = $this->makeObjectFormWidget($type, $duplicatedObject);
+        $widget->bindToController();
+
         $this->vars['objectPath'] = '';
         $this->vars['canCommit'] = $this->canCommitObject($duplicatedObject);
         $this->vars['canReset'] = $this->canResetObject($duplicatedObject);