Rector config: provide kernel for rector configuration

tests/symfony-container.php

@@ -0,0 +1,10 @@
+<?php
+
+use App\Kernel;
+
+require __DIR__ . '/bootstrap.php';
+
+$appKernel = new Kernel('test', false);
+$appKernel->boot();
+
+return $appKernel->getContainer();