[Animation] Messy curve/animation/evaluator API

Release Type: Github

Version: Latest

Platform(s): Any

Describe the bug The animation/curve API as it is is not very maintainable and quite restrictive, there's no reason now that generics supports unmanaged and interface type constraints to have two implementation of a class differing in only the generic type they chose, ex : AnimationCurveEvaluatorOptimizedVector3Group / AnimationCurveEvaluatorOptimizedVector4Group. We can replace 2/3 of the files within /Animations by implementing and adding an IInterpolation interface on our math types and including it as a constraint on our generics requiring that kind of features.