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/vendor/autoload.php

@@ -0,0 +1,7 @@
+<?php
+
+// autoload.php @generated by Composer
+
+require_once __DIR__ . '/composer/autoload_real.php';
+
+return ComposerAutoloaderInit967db673a7908b03924cd99a5cb70181::getLoader();