support chunks created by async components

[harrybin]

Hi, please support async components for screating chunks: https://serverless-stack.com/chapters/code-splitting-in-create-react-app.html currently I get

Module parse failed: Unexpected token (5:9)
You may need an appropriate loader to handle this file type.
| import MonitoringModuleContent from './MonitoringModuleContent';
| var MonitoringMainAsync = asyncComponent(function () {
>   return import('./Monitoring');
| });
| /**

https://www.npmjs.com/package/react-scripts-ts supports this, but it's outdated