Moved all event-dispatching stuff to its own module

module/EventDispatcher/functions/functions.php

@@ -0,0 +1,11 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\EventDispatcher;
+
+use Swoole\Http\Server as HttpServer;
+
+function asyncListener(HttpServer $server, string $regularListenerName): Listener\AsyncEventListener
+{
+    return new Listener\AsyncEventListener($server, $regularListenerName);
+}