Move `eddsa-proof` and `poseidon-proof` packages `get-snark-artifacts.node.ts` duplicated methods to `@zk-kit/utils`

[0xjei]

Describe the improvement you're thinking about Consider generalising the download() and getSnarkArtifacts() functions in the eddsa-proof and poseidon-proof packages and exporting them in a generic utility package such as @zk-kit/utils. This will avoid repetition and make the functions more easily reusable.

Additional context Please refer to the following link for more information: https://github.com/privacy-scaling-explorations/zk-kit/pull/173#issuecomment-1956509325

[sripwoud]

Can I take this?

[cedoor]

@sripwoud of course 👍🏽