Restore Anchors Only preset mode

[KoBeWi]

Restores the anchors-only option when picking Control anchor presets. It existed in Godot 3, but got lost at some point. See #63358 (comment) for some discussion.

godot.windows.editor.dev.x86_64_KOe4YoLkyD.mp4

[passivestar]

Often used this in unity. For convenience it might also be useful to allow inverting this logic temporarily by holding some modifier key when you click a preset button (in unity it's the Alt key)

[groud]

I've checked the current state of the editor, I'd suggest:

• Maybe we could reuse the "Anchor" toggle in the toolbar for that? It serves a very similar purpose IMO, so it could work.
• I realized this toggle does not work if you don't have a Control as a parent. I guess it could make sense to make it work in that case too (though it might be out of the scope of this PR).

[KoBeWi]

Maybe we could reuse the "Anchor" toggle in the toolbar for that? It serves a very similar purpose IMO, so it could work.

Not sure if it would be intuitive and discoverable.

I realized this toggle does not work if you don't have a Control as a parent.

That explains why it did nothing when I tried to test it. I think the button should be disabled then, which disqualifies it as an option for the new functionality.

[groud]

Not sure if it would be intuitive and discoverable.

I mean, I don't know. I think both are made to "manipulate the anchors" anyway, it's not something you do often and it's clearly visible as active or not. So I think it's a good candidate.

And well, it has an anchor icon so it's pretty clear to me IMO. Though I can understand why having a popup being influenced by a toggle in the toolbar might be a bit a bit less discoverable, but well, I think it's pretty minimal as both buttons are next to each other. (The tooltip could be updated btw, to make it clearer)

That explains why it "did nothing" when I tried to test it. I think the button should be disabled then, which disqualifies it as an option for the new functionality.

Well, as I said it could be changed so that it works. So I think it's not really an issue.

Anyway, I think I'd be happy to have a bit more feedback on what solution is better UX-wise, if anyone wants to chime in.

[AdriaandeJongh]

may I suggest the UX improvement of turning the checkbox into [ ] reposition and having it turned on by default?