Add initial files and templates for ps_emailalerts module

- Created LICENSE file for composer dependencies.
- Added autoload files: autoload_classmap.php, autoload_namespaces.php, autoload_psr4.php, autoload_real.php, and autoload_static.php.
- Initialized installed.json for composer.
- Added index.php and form templates for admin configuration.
- Implemented front-end templates for email alerts, including account management and product notifications.
- Included necessary headers and copyright notices in all new files.

modules/ps_emailalerts/mails/en/customer_qty.txt

@@ -0,0 +1,15 @@
+
+[{shop_url}] 
+
+Hi, 
+
+This item is once again in-stock.
+
+You can access the product page by clicking on the link: {product}
+[{product_link}]
+
+You can order it right now from our online shop. 		 
+
+{shop_name} [{shop_url}] powered by
+PrestaShop(tm) [http://www.prestashop.com/] 
+