feat(main): Add alert type; add template override support

upgrade/upgrade-1.9.0.php

@@ -0,0 +1,20 @@
+<?php
+
+if (!defined('_PS_VERSION_')) {
+    exit;
+}
+
+function upgrade_module_1_9_0($module)
+{
+    $existing = Db::getInstance()->executeS(
+        'SHOW COLUMNS FROM `' . _DB_PREFIX_ . 'ws_customhtml` LIKE \'template_key\''
+    );
+
+    if (empty($existing)) {
+        return true;
+    }
+
+    return Db::getInstance()->execute(
+        'ALTER TABLE `' . _DB_PREFIX_ . 'ws_customhtml` DROP COLUMN `template_key`'
+    );
+}