Add API endpoint for getting server resource utilization, closes #900

This endpoint is throttled to 15 requests per minute to avoid destroying the daemon since clients can use it.

app/Http/Controllers/Api/Client/Servers/ResourceUtilizationController.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Pterodactyl\Http\Controllers\Api\Client\Servers;
+
+use Pterodactyl\Models\Server;
+use Pterodactyl\Transformers\Api\Client\StatsTransformer;
+use Pterodactyl\Http\Controllers\Api\Client\ClientApiController;
+use Pterodactyl\Http\Requests\Api\Client\Servers\GetServerRequest;
+
+class ResourceUtilizationController extends ClientApiController
+{
+    /**
+     * Return the current resource utilization for a server.
+     *
+     * @param \Pterodactyl\Http\Requests\Api\Client\Servers\GetServerRequest $request
+     * @return array
+     */
+    public function index(GetServerRequest $request): array
+    {
+        return $this->fractal->item($request->getModel(Server::class))
+            ->transformWith($this->getTransformer(StatsTransformer::class))
+            ->toArray();
+    }
+}