Add FormatterConfiguration extender for extensions working with TextFormatter

src/Extend/FormatterConfiguration.php

@@ -0,0 +1,36 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Extend;
+
+use Flarum\Formatter\Event\Configuring;
+use Illuminate\Contracts\Container\Container;
+use Illuminate\Events\Dispatcher;
+
+class FormatterConfiguration implements Extender
+{
+    protected $callback;
+
+    public function __construct(callable $callback)
+    {
+        $this->callback = $callback;
+    }
+
+    public function apply(Container $container)
+    {
+        $container->make(Dispatcher::class)->listen(
+            Configuring::class,
+            function (Configuring $event) {
+                call_user_func($this->callback, $event->configurator);
+            }
+        );
+    }
+}