Support Animation blending

[Collinvh]

This is an enhancement I'm suggesting based of work I've did with GeckoLib so far

Either add:
A: A way to make animations blend based on two controllers
B: Add an way to get the current keyframe rotation so i can add it in customAnimations

[HappyRespawnanchor]

I also hope this feature gets added. it would be incredibly useful for me : )

[Tslat]

I'll keep this on the backburner for now

Implementing this would unfortunately require a rework of how the animationprocessor works