Send an email when a server is marked as installed (#1213)

Co-authored-by: @stanjg

app/Events/Server/Installed.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace Pterodactyl\Events\Server;
+
+use Pterodactyl\Events\Event;
+use Pterodactyl\Models\Server;
+use Illuminate\Queue\SerializesModels;
+
+class Installed extends Event
+{
+    use SerializesModels;
+
+    /**
+     * @var \Pterodactyl\Models\Server
+     */
+    public $server;
+
+    /**
+     * Create a new event instance.
+     *
+     * @var \Pterodactyl\Models\Server
+     */
+    public function __construct(Server $server)
+    {
+        $this->server = $server;
+    }
+}