Add API endpoint to get a server by external ID

app/Http/Controllers/Api/Application/Servers/ExternalServerController.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Pterodactyl\Http\Controllers\Api\Application\Servers;
+
+use Pterodactyl\Transformers\Api\Application\ServerTransformer;
+use Pterodactyl\Http\Controllers\Api\Application\ApplicationApiController;
+use Pterodactyl\Http\Requests\Api\Application\Servers\GetExternalServerRequest;
+
+class ExternalServerController extends ApplicationApiController
+{
+    /**
+     * Retrieve a specific server from the database using its external ID.
+     *
+     * @param \Pterodactyl\Http\Requests\Api\Application\Servers\GetExternalServerRequest $request
+     * @return array
+     */
+    public function index(GetExternalServerRequest $request): array
+    {
+        return $this->fractal->item($request->getServerModel())
+            ->transformWith($this->getTransformer(ServerTransformer::class))
+            ->toArray();
+    }
+}