Adds support for react 19

[JoviDeCroock]

Forwarding refs by default would be a breaking change so I've opted to add an additional entrypoint where we can export relevant pieces. This uses the existing _forwarded property to move the ref from the vnode back to props, if the user opts to leverage forwardRef all we'll do is move it to the second argument.

Alongside Context as component and our existing ref cleanup functions. We are only missing the newly added use and useActionState hooks for React 19 support, which could be exported from the new entrypoint without causing inflated bundles. In a future major version we can cut back on exports though, SuspenseList and others are basically scrapped from React.

Relates to #4613
Relates to #4618

[coveralls]

coverage: 99.616%. remained the same
when pulling 5a5e24e on support-react-19
into df1f20d on main.