Add basic subuser listing for servers

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

@@ -0,0 +1,45 @@
+<?php
+
+namespace Pterodactyl\Http\Controllers\Api\Client\Servers;
+
+use Pterodactyl\Models\Server;
+use Pterodactyl\Repositories\Eloquent\SubuserRepository;
+use Pterodactyl\Transformers\Api\Client\SubuserTransformer;
+use Pterodactyl\Http\Controllers\Api\Client\ClientApiController;
+use Pterodactyl\Http\Requests\Api\Client\Servers\Subusers\GetSubuserRequest;
+
+class SubuserController extends ClientApiController
+{
+    /**
+     * @var \Pterodactyl\Repositories\Eloquent\SubuserRepository
+     */
+    private $repository;
+
+    /**
+     * SubuserController constructor.
+     *
+     * @param \Pterodactyl\Repositories\Eloquent\SubuserRepository $repository
+     */
+    public function __construct(SubuserRepository $repository)
+    {
+        parent::__construct();
+
+        $this->repository = $repository;
+    }
+
+    /**
+     * Return the users associated with this server instance.
+     *
+     * @param \Pterodactyl\Http\Requests\Api\Client\Servers\Subusers\GetSubuserRequest $request
+     * @param \Pterodactyl\Models\Server $server
+     * @return array
+     */
+    public function index(GetSubuserRequest $request, Server $server)
+    {
+        $users = $this->repository->getSubusersForServer($server->id);
+
+        return $this->fractal->collection($users)
+            ->transformWith($this->getTransformer(SubuserTransformer::class))
+            ->toArray();
+    }
+}

app/Http/Requests/Api/Client/Servers/Subusers/GetSubuserRequest.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Pterodactyl\Http\Requests\Api\Client\Servers\Subusers;
+
+use Pterodactyl\Http\Requests\Api\Client\ClientApiRequest;
+
+class GetSubuserRequest extends ClientApiRequest
+{
+    /**
+     * Confirm that a user is able to view subusers for the specified server.
+     *
+     * @return bool
+     */
+    public function authorize(): bool
+    {
+        return $this->user()->can('view-subusers', $this->route()->parameter('server'));
+    }
+}