[GDScript 2.0] Remove confusing functions from Transform2D

[AThousandShips]

Godot version

4.0.dev

System information

Windows 10

Issue description

Built-in types are returned by value in GDScript, meaning that any modification of these (unless they are ref-counted like Array and Dictionary) by functions is ignored except when accessed as a variable itself, this seems to be reflected in how (mostly) GDScript does not expose such functions even when they exist in the class (like rotate on Transform2D/3D), however there are three exceptions to this: set_rotation set_scale set_skew on Transform2D

These can cause confusion (I for one was confused) as it is not obvious that functions called on a Transform2D cannot modify it when accessed in an array or dictionary or when from a Node2D etc., and to me it looks that these cases were overlooked

I would suggest simply removing these functions from GDScript, alternatively replacing them with non-modifying functions with_rotation with_scale with_skew if the functionality is considered important enough to keep

Steps to reproduce

To illustrate this:

var tr = Transform2D()
var arr = [Transform2D()]
print(tr)
print(arr)
tr.set_scale(Vector2(2, 2))
arr[0].set_scale(Vector2(2, 2))
print(tr)
print(arr)

And note how the transform in the array is unaffected

Minimal reproduction project

No response

[Calinou]

Related to godotengine/godot-proposals#1336.

[AThousandShips]

The set_rotation function was added in #47872 and I'm not sure why as it's never called by name there, and the rest were exposed by #52398 reasoning that the rotation one was already exposed

And to me it looks like set_rotation was only exposed there because it was used in the test project, I don't know about other areas where exposing it is justified