Implement basic sliding joint 3D

[Stefan-5422]

I filled out the boilerplate code that was already there. For now only the upper and lower limits work. I am unsure on how to implement those. However this at least provides working joints.

Another question: Is there a way to get the position of the joint Node so we can use that orientation for the axis instead of creating it based on the position of the physics bodies?

[Ughuuu]

Hi, started the ci for now, will test it locally to see. Dont know much about the joints api, i know we get a transform from godot, but unsure how to put those correctly into rapier api.

[Stefan-5422]

If it is possible I might go ahead and rewrite my code and the other implemented joints (Spherical and revolute) so they match up with the displayed gizmos in the editor.

[Ughuuu]

My guess is you would need to look at the make_functions, eg:

    fn joint_make_slider(
        &mut self,
        joint: Rid,
        body_a: Rid,
        local_ref_a: Transform3D,
        body_b: Rid,
        local_ref_b: Transform3D,
    )

Here you have 2 transforms, and 2 body rids. I think with the body rids you can get the body and their transform if needed also? Not 100% sure tbh what the local_ref_a and local_ref_b is, thats why i didnt make much progress on this also. I wanted to keep on trying with them and see if I obtain something and try to see if it works somehow. It seems godot used for joints bullet and this is their API?

I could also merge this, then merge my other PR that updates some deps, and then you can continue on that if you want.