feat: ✨ Add a bone process founction for animation making

[jerry-harm]

Add a bone process founction to solve the bone reverse problem, connect bones and add simple ik

processed bone will be like this

Of course it will be conflict with the refpose and animation, so maybe the BoolProperty in import settings need to be changed.
And empty items ATTACHMENTS will not in the right place due to the change of the bones, but there should be a solution.(maybe I should add attachments, get it's absolute location, remove the Constraints, then process the bone and add Constraints?)

[REDxEYE]

Dont really like that idea. It can be a separate a separate addon or something or generate an IK rig on top of the original skeleton and use parent constraints to copy movements, like SFM ik scripts do that

[jerry-harm]

maybe you are right, I should keep it a seperated addon