* Removed the pointers to PhysicalBone in the code, as they were unused.
* Forward ported the SkeletonIK bone scaling fix I made from Godot 3.2 to Godot 4.0.
* Fixed issue where the root bone in the IK chain would not rotate correctly.
* The issue turned out to be the update_chain function being called in solve. This would override the root bone transform incorrectly and that would cause it not to rotate after just a single solve. Removing the update_chain function fixes the issue and based on my testing there are no adverse effects.
* While the old fix on this PR (prior to a force push) required a hack fix, this new fix does not!
* Removed the update_chain function. This change doesn't appear to have any adverse effects in any of the projects I tested (including with animations, Skeleton3D or otherwise, from AnimationPlayer nodes!)
* Fixed issue where the scale of the Skeleton node would change the position of the target, causing it not to work with skeletons that have a global scale of anything but 1.
(cherry picked from commit a622649876)
71c6c85565