add SMTP mail tester

app/Notifications/MailTested.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace Pterodactyl\Notifications;
+
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Notification;
+use Pterodactyl\Models\User;
+
+class MailTested extends Notification
+{
+    /**
+     * @var \Pterodactyl\Models\User
+     */
+    private $user;
+
+    public function __construct(User $user) {
+        $this->user = $user;
+    }
+
+    public function via()
+    {
+        return ['mail'];
+    }
+
+    public function toMail()
+    {
+        return (new MailMessage)
+            ->subject('Pterodactyl Test Message')
+            ->greeting('Hello ' . $this->user->name . '!')
+            ->line('This is a test of the Pterodactyl mail system. You\'re good to go!');
+    }
+}