Add React 19 support

[shsr04]

This merge request introduces React v19 support for use-between.

The problem:

• In React 19, the hook dispatcher was moved into __CLIENT_INTERNALS_DO_NOT_USE_OR_WARN_USERS_THEY_CANNOT_UPGRADE (or on server: __SERVER_INTERNALS_DO_NOT_USE_OR_WARN_USERS_THEY_CANNOT_UPGRADE)
• The field name was changed to H
• H is no longer a static value, but it is initially null and is reassigned based on certain conditions (see renderWithHooks)

I solved this by:

• first checking the old __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED to remain compatible with React 18
• otherwise, returning a small { current } wrapper which forwards directly to the ReactSharedInternals.H property
  • no caching, current always points to the current dispatcher used by React, as expected by use-between

[betula]

Awesome!
Thanks a lot!
I'll merge it on the weekend!

[shsr04]

Cool, thanks! Regarding the pipeline errors, this can be resolved by pinning the cheerio to version 1.0.0-rc.12. https://stackoverflow.com/questions/78867305/jest-unit-tests-are-failing

Or it may be worth updating the dependencies with a reproducible lockfile.