Sumcheck loop ordering

[lucasxia01]

Brought up in a discussion with Zac over potential slowdowns in Sumcheck.

Currently we iterate over each polynomial and for each one, we call add_scaled, which loops over the same batched_poly_unshifted and batched_poly_to_be_shifted memory over and over again. Instead, we should consider switching the order of the loops so that we iterate over the polynomial indices in the outer loop and over the polynomials in the inner loop.