[Circuit] Naive `keccak_f` prototype (v1)

[mcalancea]

The purpose is to prove keccak_f using the GKR frontend. The design is "naive" in that it acts on individual bits of the Keccak state, as opposed to an optimized approach using compressed Z-coordinates + bitwise lookups & others. It is however a good way to get used to the GKR framework and it constitutes a natural baseline w.r.t better approaches.

[mcalancea]

I have an implementation that passes tests on this branch. Waiting for review from @dreamATD to close this issue.