feat: implement add_mul on Expression

[TomAFrench]

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Description

Summary of changes

This PR migrates the remaining Expression arithmetic from noirc_evaluator. The aim behind this is so that we can remove some very verbose usage of add and subtract

The add function has been changed to be the add_mul method on Expression so a + k * b can be called as a.add_mul(k, b). I'm toying with the idea that this would be better named as mul_add as we're first multiplying then adding so this may be clearer. add_mul has had some refactoring applied to improve readability.

The + and - operator implementations have been updated to use add_mul under the hood as we should always have a + b == a.add_mul(1, b) which may not be the case otherwise.

I've also implemented * which replaces the mul function from noirc_evaluator.

Dependency additions / changes

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Test additions / changes

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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.

Additional context

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[kevaundray]

I'm happy with moving these into acvm, I think we need to have a clean-up of the logic inside of these functions, in particular the fact that we need Ordering seems like an abstraction leak. This is not a blocker for this PR though