Add Creative Elements templates and update index files

- Introduced new templates for catalog, checkout, contact, and error pages.
- Implemented caching headers and redirection in index.php files across various directories.
- Enhanced product and layout templates for better integration with Creative Elements.
- Added backoffice header styles and scripts for improved UI/UX in the admin panel.

modules/creativeelements/views/js/backoffice.js

@@ -0,0 +1,12 @@
+/*!
+ * Creative Elements - live PageBuilder [in-stock]
+ * Copyright 2019-2022 WebshopWorks.com
+ */
+
+document.addEventListener('DOMContentLoaded', function() {
+	$('body').on('click', '.module-item[data-tech-name=creativeelements] .module_action_menu_upgrade', function (e) {
+		e.preventDefault();
+		e.stopPropagation();
+		window.open('https://creativeelements.webshopworks.com/buy-license?utm_source=upgrade&utm_campaign=in-stock&utm_medium=backoffice');
+	});
+});