[7.1] Reload preview window (again) after element create

This has been removed during refactoring the element editor
into a custom web-component in AlchemyCMS#2614

This restores the behavior.

app/views/alchemy/admin/elements/create.js.erb

@@ -28,6 +28,7 @@
 
   Alchemy.growl('<%= Alchemy.t(:successfully_added_element) %>');
   Alchemy.closeCurrentDialog();
+  Alchemy.reloadPreview();
 
   el = document.querySelector('#element_<%= @element.id %>');
   el.focusElement();