Split nargo crate into nargo_core and nargo_cli

[TomAFrench]

Problem

There's currently no good way to prove/verify from an external program other than by shelling out to call into nargo. We should have a simple rust library which exposes the core functionality of nargo, this would then be used by external rust programs and also feed into our wasm builds to keep as much shared logic as possible.

Proposed solution

We should split the nargo crate into two. nargo should contain any logic which is specific to the command line, e.g. CLI command definitions, package resolution, etc. whereas nargo-core should hold any reusable logic which would be useful to be used as a library.

Alternatives considered

No response

Additional context

No response

Submission Checklist

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