Improve Chorus Crab animations

Is your feature request related to a problem? Please describe.

The current Chorus Crab walking animation is... okay? Certainly not out-of-place in a game with the vanilla horse walking cycle. But I would like a better scuttle as well as some nice idle animations if not an attack move that swings the pincers

Describe the solution you'd like

The Crab model already (v0.3.0-beta1) has the necessary bones to support these animations, so it should just be a matter of coding the correct cycles (and, if necessary, implementing a custom RenderState instead of the current LivingEntityRenderState).

Describe alternatives you've considered

Leave as-is; switch to GeckoLib or a framework that makes this easier

Additional context