fix: ignore implicit unbound named generic when searching trait impls

[asterite]

Description

Problem

Resolves #9168

Summary

I'm unsure about this change but in the small code snippet for the test the only thing that was failing was the trait impl lookup. This is the code:

pub trait Other {
    let N: u32;
}
pub trait Trait<T>
where
    T: Other,
{}
impl Other for Field {
    let N: u32 = 1;
}
impl Trait<Field> for i32 {}

When analyzing impl Trait<Field> for i32 we check if Field: Other we try to find an impl for Field that matches Other<N = implicitly_added_named_generic>. It will then try to unify that implicitly added named generic with 1 and fail.

Maybe an alternative is to replace those implicitly added named generics here with fresh type variables? In any case these bindings aren't committed in this lookup....

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: 8f48b3f	Previous: 38997a8	Ratio
test_report_AztecProtocol_aztec-packages_noir-projects_noir-protocol-circuits_crates_reset-kernel-lib	2 s	1 s	2
test_report_AztecProtocol_aztec-packages_noir-projects_noir-protocol-circuits_crates_rollup-lib	4 s	3 s	1.33
test_report_zkpassport_noir-ecdsa_	3 s	1 s	3

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

CC: @TomAFrench

[asterite]

Closed in favor of #9352