What problem does this feature solve?

Example use case:
A static generated app with thousands of routes, like an e-commerce having a route for each product.
Apart from scheduling nuxt generate to run periodically and generate all static and dynamic routes, it would be nice to have the possibility to generate the static files for a single route, for example in a hook when the related ba

多实例（主要是v2ray多实例）需求，主要是两个场景，且难以用其它方式替代。请拨冗考虑，未来是否可以增加此特性。

场景1、代理链式转发

在 #742 中关于代理链式转发的讨论，使用proxySettings代理出站流量的方向是对的，但在实操中，结合机场的订阅，需要将机场的信息编辑到复杂路由的json配置中，当切换线路时非常的麻烦。

我现在的做法，是机场的代理提供一个本地socks5服务，比如端口为10801，v2ray中配置一个socks协议的outbound，作为vmess的proxySetting。整个链路大致是这样的:

  浏览器  -> 
  # 代理
  socks://127.0.0.1:1080 -> vmess outbound (proxySetting on socks)-> socks outbound -> 
  #

"Babel 7.8.0 supports the new ECMAScript 2020 features by default: you don't need to enable individual plugins for nullish coalescing (??), optional chaining (?.) and dynamic import() anymore with preset-env." - https://babeljs.io/blog/2020/01/11/7.8.0

We should update zero to latest babel and add an integration test for these features. I think the right change will be [here](https://gith

https://emotion.sh/

After this change in Material UI: mui-org/material-ui#6115