Improve wraparound check parameter search

The improvements come as:
- We now look for the smallest num_wr_successes that satisfies soundness,
  then searches for alpha (if possible) that can satisfy ZK.
- Then combine with dimension to compute the number of proofs to
  satisfy the overall soundness.

Turns out with num_frac_bits = 24, neither Field56, nor Field48
can satisfy the field size requirement in wraparound checks.
But with num_frac_bits = 20, Field56, we actually find a case where
num_wr_successes < num_wr_checks.