* Bump to arkworks-0.4.0

* Replace remaining usages of `msm_bigint` with `msm_unchecked`

Using `msm_unchecked` instead of `msm_bigint` allows to delete the BigInt conversion code by letting the library take care of it.

* feat: faster sum check prover and multilinear kzg batching open

* fix: add comment about why we combine polys that have the same opening point

* fix: remove the unnecessary last eval increment

- use sumcheck to batch open PCS
- split Prod and witness into two batches
- benchmark code

Co-authored-by: Charles Chen <chancharles92@gmail.com>