The new Unity animation system. It uses burst, which makes it speedy.
General Notes:
The RigBuilder component is so called because it “Builds” a hierarchy of constraints into a set of AnimationJobs. 1)
The RigBuilder Build step happens on Awake[research needed]. So, the ordering of constraints cannot be modified at runtime by re-ordering the rig itself.
All Constraint components must be under a Rig component.