replace with custom superagent based on fetch API

src/routes/filemanager.js

@@ -40,7 +40,7 @@ function proxy(kind) {
           };
 
           const sftpReq = http.request(opts, function (sftpRes) {
-              res.writeHead(sftpRes.statusCode, sftpRes.headers);
+              res.writeHead(sftpRes.status, sftpRes.headers);
               // note: these are intentionally not handled. response has already been written. do not forward to connect-lastmile
               // sftpRes.on('error', (error) => next(new HttpError(500, `filemanager error: ${error.message} ${error.code}`)));
               // sftpRes.on('end', () => next());