[feat] Support React 19

[acouch]

Does your feature request relate to a specific USWDS component?

No.

What USWDS Version is this feature present in?

NA

Is your feature request related to a problem? Please describe.

React 19 RC was released in April: https://react.dev/blog/2024/04/25/react-19

It is unclear exactly when React 19 will drop, however this project could start to prep. I'd be happy to put some cycles into this myself, though not sure how big of an effort it will be.

The upgrade to 18 didn't appear to be too painful https://github.com/trussworks/react-uswds/pull/2714/files

Describe the solution you'd like

• Stage a branch that works with the release candidate
• Determine whether multiple versions could be supported
• Ensure that there is a consensus on any questions that arise with the upgrade

Would be ideal to have a solution near or before React 19's release.

Describe alternatives you've considered

Could always not support React 19 😄

[sbolel]

I started the upgrade here: #3083 -- would love to collaborate if anyone is interested!