fix: add support for nested arrays returned by oracles

[guipublic]

Description

Problem*

Resolves #4561

Summary*

Generates brillig arrays of arrays during brillig-gen for types having nested arrays.
Populate these nested brillig arrays in the brillig VM when data returned from oracles does not match the size of the outer array

Additional Context

For this to work, it is required that the oracle returns flatten values, although its Noir signature is a nested type.
It's certainly possible to deserialise nested json arrays but I could not get it done easily so it'll be better handled in a separate PR.

Documentation*

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[github-actions]

🚀 Deployed on https://666ad6247e757b1143f882d4--noir-docs.netlify.app

[TomAFrench]

Can you add a test case for this?

[guipublic]

Can you add a test case for this?

I wonder how to unit test Oracles?

[vezenovm]

I wonder how to unit test Oracles?

You should be able to use the mock oracle

[guipublic]

I wonder how to unit test Oracles?

You should be able to use the mock oracle

Thank you, I added a test using a mock oracle

[TomAFrench]

We should be able to refactor this so that we remove some duplication on how we're writing arrays into memory. I'm ok taking in some tech debt here however. If we're not handling this in this PR then can you add make an issue to handle this in future?

We should add some extra test cases involving nested types including struts however.