Rewrite tests for OAuth2 validate and auth code complete steps [skip ci]

api/components/OAuth2/Entities/UserEntity.php

@@ -0,0 +1,16 @@
+<?php
+declare(strict_types=1);
+
+namespace api\components\OAuth2\Entities;
+
+use League\OAuth2\Server\Entities\Traits\EntityTrait;
+use League\OAuth2\Server\Entities\UserEntityInterface;
+
+class UserEntity implements UserEntityInterface {
+    use EntityTrait;
+
+    public function __construct($id) {
+        $this->identifier = $id;
+    }
+
+}