Build Nargo CLI releases using nix

[TomAFrench]

Problem

We currently have to build the barretenberg.wasm binary and install cross in CI on each run of publish.yml. This is ok as we cache the build outputs here but it would be preferable to have this provided by nix.

Happy Case

We should create a nix env which contains the barretenberg wasm binary and installs cross so we don't need to handle this in CI.

Alternatives Considered

No response

Additional Context

#2211 (comment)

Would you like to submit a PR for this Issue?

No

Support Needs

No response