[Web][Tests] Add PHPUnit setup and imapsync module tests

tests/php/Support/LegacyAclCalls.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mailcow\Tests\Support;
+
+/**
+ * Calls recorded by the legacy ACL stand-ins in legacy_acl_functions.php.
+ */
+class LegacyAclCalls
+{
+    public static array $calls = [];
+}