Implement IMAP email-to-ticket gateway

tools/setup.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+if (PHP_SAPI !== 'cli') {
+    http_response_code(404);
+    exit;
+}
+
+require dirname(__DIR__, 3) . '/load.php';
+$di['mod_service']('mailgateway')->setup();
+echo "Mail Gateway tables and sender-mismatch email template are ready.\n";