An Inspector rework for all things GUI

[philippedcote]

Coming from top GUI design tools like Figma, it’s a bit cumbersome to develop every possible Toggle Items in the Inspector whereas it could be much more visual and condensed, like this:

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Using tabs could also help to separate "Advanced" settings from the rest.

[Calinou]

This was already reworked for 4.0 in godotengine/godot#55157 (see the original proposal). It relies on backwards-incompatible changes, so it can't be backported to 3.x.