Radio buttons

[tim-x-y-z]

Hi thanks again for the amazing project, here's a trial of contribution - to be caveated i am very new to react / JS so there might very well be better ways to do this but hope it helps.

trying to implement radio as described in issue: https://github.com/pydantic/FastUI/issues/160

Currrently it looks like this:

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.

Files	Patch %	Lines
src/python-fastui/fastui/json_schema.py	85.71%	1 Missing :warning:

:loudspeaker: Thoughts on this report? Let us know!

[samuelcolvin]

Overall, this is looking pretty good, thank you.