Feature Request: rollup plugin

I want to use jiti to speed up packaging during development.

I can do this with sucrase,

![Screen Shot 2021-03-20 at 00 29 30](https://user-images.githubusercontent.com/69119532/111813107-bc366f00-8913-11eb-87f6-a6beb70f980d.png)
