Add endpoint to return startup variables; send back modified startup when a variable is edited

app/Http/Requests/Api/Client/Servers/Startup/GetStartupRequest.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Pterodactyl\Http\Requests\Api\Client\Servers\Startup;
+
+use Pterodactyl\Models\Permission;
+use Pterodactyl\Http\Requests\Api\Client\ClientApiRequest;
+
+class GetStartupRequest extends ClientApiRequest
+{
+    /**
+     * @return string
+     */
+    public function permission()
+    {
+        return Permission::ACTION_STARTUP_READ;
+    }
+}