GPU plotting preparation

[nazar-pc]

Some changes extracted from local branch that will be helpful for GPU plotting when it is introduced.

rust-kzg repo update is needed to include grandinetech/rust-kzg#263 that we'll be using in FFI calls to GPU.

K constant was not previously explicitly exposed for proof of space and pool plotter will allow us to combine CPU and GPU plotters into one virtual plotter.

Code contributor checklist:

• I have read, understood and followed contributing guide

[teor2345]

Seems like there are some "invalid Scalar" errors in the tests, but I can't find where they are coming from in the code changes. Maybe they're from a dependency change?

[nazar-pc]

Yeah, looks like caused by blst upgrade, I'll take a look at it

[nazar-pc]

And here is the reason: grandinetech/rust-kzg#265

[nazar-pc]

@dariolina see ethereum/c-kzg-4844#305 and linked PRs, should we switch to big-endian encoding after Gemini 3h as well?

[dariolina]

Ugh...
We would want to keep compatibility aspirations with Ethereum. As long as commitments to different vectors are still unique and verifiable, we should be fine
Can you try the switch and see if our encoded public KZG parameters still match ?

[nazar-pc]

KZG parameters are irrelevant here, this is about data processing during archiving and plotting

[dariolina]

Then that data processing where the endianess matters is not part of consensus, so it depends if you have counter-arguments why not switch?

[nazar-pc]

I do not have any counter-arguments, but we can only do that after Gemini 3h

[teor2345]

Looks good to me, but I don't have enough context to fully approve.