Preview while editing

[cristinallamas]

Package

I’m not sure

Describe the feature request

Describe the solution you'd like

In order to improve the editorial experience and avoid mixing of visual elements and confusion it would be great to have the preview iframe in the Edit page, much like the Preview button works at the moment in core. something like the Sanity.io preview works

intead of

Describe alternatives you've considered

I have not encountered an alternative to a live preview for a Drupal+NextJS site

Additional context

The current solution, which is the iframe for preview showing in the view tag presents the user with double preview, one in the theme used and one in the NextJS site, this leads to a confused and not great editorial experience.

Proposed solution