Improve the default size of 3D shapes and meshes (Box, Capsule, and Cylinder)

[aaronfranke]

Implements and closes godotengine/godot-proposals#3732

The specific values are up for discussion in the above proposal, but I think what's currently in this PR is quite good.

I don't really have an opinion on the CSGTorus3D changes, they were copied from https://github.com/godotengine/godot/pull/49729/files#diff-a81f2e3a53dfacfdb0037de9538db28d5646ae0c3a11a52eca1caa5d665dfd1cR1676-R1678

Breaks compat, but we have already broken compatibility with these shapes for 4.0 so changing this is not a big deal.

[JFonS]

I agree with the new Box defaults, but I don't really like the cylinder/capsule ones.

I would rather have a 0.5 default radius and a 1.0 default height. So they follow the same rationale of "a scale of 7 means it's 7 meters wide" that is mentioned in the proposal.

In any case, there's never going to be a perfect default value, but if we are going to change any defaults, it should be done before alpha.

[akien-mga]

After discussion in a PR meeting we suggesting using:

• 1.0 for Box (as in this PR)
• Radius 0.5 and height 2.0 for capsule/cylinder.

[nathanfranke]

As long as it follows the style guide,

Suggested change

	Vector3 size = Vector3(1, 1, 1);
	Vector3 size(1, 1, 1);

[akien-mga]

That's actually a style that we don't really use in the codebase so far, so it's better not to start using it as it adds inconsistency in the codebase.

[aaronfranke]

This PR has been updated so that the capsule and cylinder defaults are now 0.5 radius and 2.0 height. While I still think 0.25 radius and 1.75 height is better, 0.5 radius and 2.0 height is still very good and it has consensus.

[akien-mga]

Thanks!

[Calinou]

It seems SphereMesh is now twice as large as BoxMesh by default. Should we make spheres smaller to match BoxMesh again? The same applies to CSGSphere3D.

[aaronfranke]

@Calinou I'm not sure. On one hand, that makes sense. On the other hand, it's simpler to have the sphere be a radius of 1.0 as the default, and people usually think of circular shapes in terms of the radius. Either way seems fine to me.

EDIT: Also, a radius of 0.5 would be more consistent with the ends of the new capsule size. So perhaps it's better.