Nested sub-inspectors misbehave for properties with their own editors

[KoBeWi]

Godot version

3.x 4b50cd9

System information

W10

Issue description

When you try to edit some resource inside another resource inside a node, the parent resource gets folded. Doesn't happen on master.

Steps to reproduce

1. Add Control node
2. Add a Theme to theme property
3. Add a default font
4. Try to unfold the font
5. Theme gets folded and you can't edit the font

Minimal reproduction project

No response

[YuriSizov]

Okay, these steps didn't break anything for me, but adding a resource to a theme type (like a stylebox or a font to, say, the Label type) breaks in the described way. And in master too.

[YuriSizov]

Good news, it's not technically a regression. Bad news, it's not actually a good news. The root cause is the same as #29873 and #47514 (and a bunch of others).

Because the new Theme editor considers styleboxes and fonts as its supported resources (so that the editor doesn't close when you start editing a stylebox inside of a theme), the inspector freaks out. It thinks that the stylebox needs a new bottom editor to open, and closes all existing editors (and folds all related resources, even though they are children of those resources).

As such, this will probably be fixed by either #45085 or a new similar solution with proper support for multiple contextual editors. To make sure that we can release 3.4, I've made a PR that disables sub-inspectors for such resources that have contextual editors (#52984). This prevents the related folding issues and makes editor usable.