Optimize CycleFold circuit MSM approach

[arnaucube]

In CycleFold we want to compute
$P_{folded} = P_0 + r \cdot P_1 + r^2 \cdot P_2 + r^3 \cdot P_3 + ... + r^{n-2} \cdot P_{n-2} + r^{n-1} \cdot P_{n-1}$, since the scalars follow the pattern r^i Youssef El Housni ( @yelhousni ) proposed to update the approach of the CycleFold circuit to reduce the number of constraints needed, by computing
$P_{folded} = (((P_{n-1} \cdot r + P_{n-2}) \cdot r + P_{n-3})... ) \cdot r + P_0$.

By itself, this update reduces the number of constraints as the number of points being folded in the CycleFold circuit grows. But it also has impact at the HyperNova circuit, where it removes the need of using the bit representations of the powers of the random value, substancially reducing the amount of constraints used by the HyperNova AugmentedFCircuit.

The number of constraints difference in the CycleFold circuit and in the HyperNova's AugmentedFCircuit:

• CycleFold circuit:

num points*	old	new	diff
2	1_354	1_354	0
3	2_683	2_554	-129
4	4_012	3_754	-258
8	9_328	8_554	-744
16	19_960	18_154	-1_806
32	41_224	37_354	-3_870
64	83_752	75_754	-7_998
128	168_808	152_554	-16_254
1024	1_359_592	1_227_754	-131_838

*num points: number of points being folded by the CycleFold circuit.

• HyperNova AugmentedFCircuit circuit

folded instances*	old	new	diff
5	90_285	80_150	-10_135
10	144_894	117_655	-27_239
20	249_839	192_949	-56_890
40	463_078	344_448	-118_630

*folded instances: folded instances per step, half of them being LCCCS and the other half CCCS.

[CPerezz]

Awesome!

This trick is also used in the SumCheck circuit implementation! IIRC it's called butterfly summation or something like this? Unsure, I might not remember well.

The trick is cool, we also get some savings and, finally, it also simplifies some parts of the codebase!

LGTM!