Challenge generator should absorb commitments before squeezing during batching operations

[mmagician]

As per the discussion in #139

[Pratyush]

Not only commitments, but also the evaluation points, the evaluations, and the proofs.

(This is in the context of batch verification of two different proofs.)

[mratsim]

This paper reviewed in-depth transcript implementation failures:

• Weak Fiat-Shamir Attacks on Modern Proof Systems
  Quang Dao, Jim Miller, Opal Wright, Paul Grubbs, 2023
  https://eprint.iacr.org/2023/691