Feature request: Support Iframes

[fraaalk]

I stumbled upon a Tweet on X (https://twitter.com/alexandereardon/status/1765523608682795227) where Alex Reardon shows off his drag and drop lib with iframe support.

I think adding iframe support would be an awesome feature, which will help developers to build even better things with the drag-and-drop lib from formkit.

This would help us to improve our page-builder and display the whole page with its components in an resizable iframe and easily offer a preview of the page in different viewport sizes but keep the component lib (with drag-n-drop) in the main frame.