Allow to open nested forms and repeater item forms in a modal.

[der-On]

The idea is, that if you add/edit an repeater item or the contents of a nested form you open those fields in a dialog that also allows usage of tabs within that dialog.

This should also be possible to use nested dialogs, so I can eg. open a nested form dialog from within a repeater item dialog.

I could image this beeing enabled by simply adding a editMode: modal vs editMode: inline to nestedforms or repeaters.

For a preview to work one should provide either a previewForm with fields that will be readonly like in the preview mode of model forms or a previewPartial that renders the preview completely custom.

Here is a clickable prototype: https://penpot.studiobosco.de/#/view/76f0175f-eb72-811f-8004-2ef7291ec8a0?page-id=cdd86b65-fa64-8061-8003-b7ff3a2d6c8c&section=interactions&index=0&share-id=ab51903d-c349-8129-8005-312c0a860dd3