Implement generator of Nova proof and verifier's key serialised to JSONs

[storojs72]

Codebase of the verifier is focused on two distinct reference implementations: "regular" Spartan and, so called, pp-spartan. In future the amount of targeted references may be increased. Every reference produces own version of proof and verifier key JSONs required for running the verification logic in Solidity, which we used to hardcode in the repository. It would be nice to have a Rust command-line application that allows generating different instances of mentioned JSONs by specifying particular version of reference and particular proving-verifying test (like for example this one, which we use heavily).

An interesting approach of using multiple dependencies of the same crate in Rust application is serde-many.

[artem-bakuta]

Have created PR to resolve this issue, take a look link to Nova repo PR

[storojs72]

lurk-lang/Nova#39