chore: Perform Circuit optimization in nargo

[TomAFrench]

Description

Problem*

This PR removes all knowledge of which backend is being used from the driver + evaluator. Generic ACIR is then returned and is optimized in nargo.

The changes to the backend interface have thrown up an annoyance in that we need to optimize the circuit before we preprocess the circuit rather than allowing the backend to handle this itself. The current situation downloads a CRS based on the size of the unoptimized circuit rather than the one the backend will actually be using.

Related to #1102

Summary*

This PR sets out to

Example

Before:

After:

Documentation

• This PR requires documentation updates when merged.

  • I will submit a noir-lang/docs PR.
  • I will request for and support Dev Rel's help in documenting this PR.

Additional Context

PR Checklist*

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

[guipublic]

This PR breaks #1333

[TomAFrench]

@phated Relevant to LSP conversation.

[TomAFrench]

Merged something to fix all of the merge conflicts. I'm getting test failures which correspond to unoptimized ACIR trying to be passed to bberg somewhere which we need to address.

[TomAFrench]

This PR pulls the ACIR optimization up from noirc_driver to nargo_cli so that we can start thinking of ACIR optimization as a separate process to ACIR generation.

This is desirable for a number of reasons, including:

• Generation of a backend-agnostic test suite of ACIR programs + initial witnesses which various backends can test against.
• Simplification of the user flow with pluggable backends as optimisation can be delegated to the backend which removes a round of communication.

moving towards compilation then optimization being separate so we can eventually compile without a backend