Improve hover effect

[formfcw]

Scope

This PR adds two things:

1. When hovering over elements, a bounding rect appears to indicate where the edit button that also appears belongs.
2. When hovering over a nested element, the parent element doesn't show its edit button anymore and the bounding rect appears with less opacity.

[linear]

WEB-659 Make hover effect a bit more precise

[AlexGaillard]

Just one small change.

Otherwise much better UX here 😄

[AlexGaillard]

🆒🫘