Move JsxDOM types etc. into @rescript/react(-dom)

[cknitt]

Proposal:

• Remove modules Dom, Dom_storage, Dom_storage2 from the @rescript/runtime package
• Instead of those, vendor the base package of experimental-webapi
• Make the vendored @rescript/react depend on that
• Split off @rescript/react-dom
• Move JsxDOM/JsxDOMStyle/JsxEvent into @rescript/react-dom
• Make everything work 🙂
• Also make it work/test with rescript-react-native and a with non-React JSX runtime like Xote

Note that any vendoring here (@rescript/react, @rescript/react-dom, relevant parts of webapi and rescript-react-native/Xote) does not mean moving the source of truth for these packages into the compiler repo. It's just for easier and quicker iteration while moving things around.

Once the new shape has crystallized, things need to be synced back to the respective repos.

[dkirchhof]

I started to work on it here:

rescript-lang/rescript-react#151
#8282

Now, after about 2 months, there are a lot of conflicts. Maybe it's a good starting point. Maybe not. Could fix the merge conflicts first, if this is going in the right direction.

[tsnobip]

@cknitt do we want to split off @rescript/react-dom to its own package or should we rather use rewatch "features"?

[cknitt]

Not sure. I was originally leaning towards splitting it off to match what people would be expecting following the npm package structure (react/react-dom, @types/react/@types/react-dom).

OTOH maybe keeping it a single package with all features on by default would improve compatibility/ease migration.

[tsnobip]

You're right, those are separate packages in js so it'd make sense to stick to the same structure.