Wasm bindings

## What problem does this solve or what need does it fill?

It seems that the wasm bindings don't exist anymore, so it's difficult to use this library from JS-land. I made a [JS terminal library](https://github.com/manaflair/mylittledom) many years ago using Yoga and I'd like to rebuild it, evaluating new tech options.

## What solution would you like?

Ideally a basic wasm API would be great. If not possible, it'd be useful to at least annotate FlexboxLayout & its enums with the wasm-bindgen attributes (cf second part of this answer here: https://stackoverflow.com/a/65336309), as there's a lot of them and duplicating them would be very painful.

## What alternative(s) have you considered?

Keep using Yoga, but I'm interested to follow a bit the development here.

Review the current FlexboxLayout and enum definitions and determine whether a basic WebAssembly API or wasm-bindgen annotations are feasible. Compare the available bindings with the requested JavaScript use case; done means an agreed binding approach is implemented and usable from JavaScript, or the annotated API is complete.

Written by the indexing model from the issue text.