fix(parser): do not use Ident::default()

[asterite]

Description

Problem

Similar to #8178, Ident::default() ends up using a default/dummy location that would sometimes crash the LSP server.

Summary

One case where it crashed was if you had code like this:

#[test]
fn () {
    let x = 1;
    let y = 2;
}

The name is missing. In my case that happens when I rename the function: I use VIM mode so the command first removes the entire name and lets me type a new one.

The error happened because in this case the parser ended up using Ident::default() for the name, and when LSP tried to use that location it crashed.

In addition to this I improved the error message shown in this case. Previously it would not continue parsing the function and error on each successive token. Now the parser will assume the function definition continues if a ( or < comes next.

Finally, checking the error messages now use assert_snapshot! which will be handy if we later change/improve the produced error messages.

Additional Context

I'm trying to fix these LSP bugs as soon as I find them because I usually left them for later, but then I couldn't remember how to trigger them.

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: 85478a0	Previous: ad56ce6	Ratio
test_report_noir-lang_noir_bigcurve_	284 s	231 s	1.23

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

CC: @TomAFrench