Introduce RequestUtil

Abstracts access to following request attributes:

- actor
- session
- locale
- route name

src/Http/RequestUtil.php

@@ -0,0 +1,56 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Http;
+
+use Flarum\User\User;
+use Illuminate\Contracts\Session\Session;
+use Psr\Http\Message\ServerRequestInterface as Request;
+
+class RequestUtil
+{
+    public static function getActor(Request $request): User {
+        return $request->getAttribute('actor');
+    }
+
+    public function withActor(Request $request, User $actor): Request
+    {
+        return $request->withAttribute('actor', $actor);
+    }
+
+    public function getSession(Request $request): Session
+    {
+        return $request->getAttribute('session');
+    }
+
+    public function withSession(Request $request, Session $session): Request
+    {
+        return $request->withAttribute('session', $session);
+    }
+
+    public function getLocale(Request $request): string
+    {
+        return $request->getAttribute('bypassCsrfToken');
+    }
+
+    public function withLocale(Request $request, string $locale): Request
+    {
+        return $request->withAttribute('locale', $locale);
+    }
+
+    public function getRouteName(Request $request): string
+    {
+        return $request->getAttribute('routeName');
+    }
+
+    public function withRouteName(Request $request, string $routeName): Request
+    {
+        return $request->withAttribute('routeName', $routeName);
+    }
+}