Implement CRBA with jax.lax.scan

[diegoferigo]

This PR implements the CRBA algorithm with jax.lax.scan, with two main benefits:

• Reduction in JIT compilation time especially for model with many DoF(Optimize compilation time of CRBA #5)
• Forward and backward AD support (Investigate AD (automatic differentiation) support #4)

This goes also in the direction of #12. Unfortunately, as it was already clear, the readability of the algorithm is affected by the switch.

CRBA Algorithm

Here below a summary of the new CRBA performance compared to the previous implementation:

Model name	DoFs	JIT time	JIT time speedup	Runtime	Runtime speedup
panda	9	1.35 s	x3.7	569 µs	x1.01
iCubGazeboV2_5	32	5.67 s	x7	1.17 ms	x1.01

The JIT time is now much lower than before. Instead, the runtime didn't change.