[proof chunk] WIP: rw_table witness commitment to derive challenge

[hero78119]

Contents

• introduce get_rwtable_cols_commitment which will be used to get rw_table column witnesses commitment
• [temporarily] hardcode challenge value in aggregation circuit and remove hardcode later

Other notes

Need to upgrade PSE-halo2 api empty_lagrange_assigned visibility to public.

Design rationale

Implement commitment follow halo2 create_proof to collect witness and commit

[hero78119]

Hi @CeciliaZ030 this PR introduce new api get_rwtable_cols_commitment so we can derive unblinded advice column commitment in the same way to compute permutation challenge in bus-mapping, FYI

[CeciliaZ030]

I wonder if there's an easier way to do this other than instantiating a new circuit in get_rwtable_cols_commitment, for example changing the existing Challenge API to squeeze challenge from specified unblinded_advice_column during the assignment phase? In that way the whole design will change 😅 but one solution could be uniting the Challenge and UserChallenge to one big thing?
I don't know I'm just brainstorming.

[hero78119]

Covered in PR #1773