Code splitting

[AdrienLemaire]

We're interested in using the @headlessui/react component Transition, but do not have a need for the other components at this time.

It would be great to allow importing components from their own source, to help builders like webpack with code splitting.

Current:

import { Transition } from "@headlessui/react"; 

=> bundles all headlessui react components in the build.

Wanted:

import Transition from "@headlessui/react/Transition"; 

=> Only the Transition code is bundled.