chore: switch integration tests to mirror CLI usage

[TomAFrench]

Related issue(s)

Resolves #1177 (comment)

Description

Summary of changes

This PR changes the integration tests to work using the CLI directly to ensure exact parity between this and real-world usage. i.e. rather than using prove_and_verify we actually use nargo prove and nargo verify.

As part of this I've done some general refactoring as this code is unnecessarily complex (3 layers of nesting to just iterate through test cases).

Dependency additions / changes

Test additions / changes

Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt with default settings.
• I have linked this PR to the issue(s) that it resolves.
• I have reviewed the changes on GitHub, line by line.
• I have ensured all changes are covered in the description.

Documentation needs

• This PR requires documentation updates when merged.

Additional context

[TomAFrench]

@kevaundray This adds another ~10mins to the ubuntu run (up from 18mins)

[TomAFrench]

I've separated all the readability improvements into #1180 so we can merge those even in the case we don't go ahead with this change. (plus it will highlight the substantive changes here more clearly)

[kevaundray]

Ah thats horrible

[jfecher]

What is the reasoning for the extra 10 minutes of runtime?
Honestly that seems like a large enough downgrade that I'm wary of merging this at all

[TomAFrench]

Let's park this pending #1180

[TomAFrench]

Comparing this PR with master.

There's a 5 second difference between the two now that we're not proving and verifying.

[jfecher]

👍