fix: Make Ssa-gen use existing reference when compiling &mut foo.bar.baz

[jfecher]

Description

Problem*

Resolves #9251
This fixes the final false part of the table in #9250

Summary*

When you did &mut foo.bar.baz previously this would translate to &mut (*foo).bar.baz internally due to . performing auto dereferencing. When we have a leading &mut however we do not want this behavior and want . to implicitly perform as an offset instead. We didn't find this before because it was only observable when you had another referenced aliased inside the struct, as in the linked issue.

To fix this I've:

• Created a new function elaborate_reference which is only called when elaborating the rhs of &mut rhs
• elaborate_reference passes a flag to elaborate member access telling it not to automatically dereference and return a boolean if it did pass through a reference
• If this returned flag is true we need to skip the &mut because the member access is already returning a reference, so we do not get a &mut &mut T.
• Instead of replacing the unary op with just its rhs we need to keep it with a new skip: bool flag so that nargo expand still prints the &mut without removing it, and --show-monomorphized does as well.

Additional Context

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]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Test Suite Duration'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.20.

Benchmark suite	Current: 00d967a	Previous: 6abff2f	Ratio
test_report_AztecProtocol_aztec-packages_noir-projects_aztec-nr	6 s	3 s	2
test_report_AztecProtocol_aztec-packages_noir-projects_noir-protocol-circuits_crates_blob	3 s	2 s	1.50
test_report_AztecProtocol_aztec-packages_noir-projects_noir-protocol-circuits_crates_rollup-lib	3 s	2 s	1.50
test_report_zkpassport_noir-ecdsa_	3 s	1 s	3

This comment was automatically generated by workflow using github-action-benchmark.

CC: @TomAFrench

[asterite]

Looks good!