add links to enter / exit folders

Reviewed-on: sites/file-explorer#5

src/Service/Twig/RoutingService.php

@@ -0,0 +1,23 @@
+<?php
+declare(strict_types=1);
+
+namespace App\Service\Twig;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
+
+class RoutingService
+{
+    public function __construct(private UrlGeneratorInterface $urlGenerator)
+    {
+    }
+
+    public function goBack(Request $request): string
+    {
+        $dirsString = $request->attributes->get('dirs', '');
+        $dirs = explode('/', $dirsString);
+        array_pop($dirs);
+
+        return $this->urlGenerator->generate('app_home', ['dirs' => implode('/', $dirs)]);
+    }
+}