fix: parse AsTraitPath in type expressions

[asterite]

Description

Problem

Resolves #5794

Summary

I don't know if I missed this while porting the old parser.

That said, this currently doesn't work if AsTraitPath is used in a function signature. That is, this doesn't compile:

use std::mem::zeroed;

trait Trait {
    let N: u32;
}

impl Trait for Field {
    let N: u32 = 10;
}

fn main() {}

fn foo(x: [Field; <Field as Trait>::N]) {} // No matching impl found for `Field: Trait<N = _>`

I think the reason is that function signatures are checked before impls are processed, not sure. In any case this PR at least makes the use case in the linked issue work.

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.

[TomAFrench]

LGTM

[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: a67cef6	Previous: 566de3f	Ratio
test_report_zkpassport_noir_rsa_	2 s	1 s	2

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

CC: @TomAFrench