Improve document symbol hierarchy to match rust-analyzer layout

[JoshuaBatty]

Description

Changes document symbols to provide a richer code outline view with nested hierarchies and type information, similar to rust-analyzer's implementation. This improves code navigation by showing relationships between elements (e.g., structs with their fields, functions with their variables) and includes type annotations for better understanding.

Key improvements:

• Nested symbol hierarchy instead of flat list
• Type information in symbol details
• Function signatures with parameter/return types
• Proper parent-child relationships for all code elements
• Better outline view organization

Note: the performance impact is due to the get_range_from_span function which can't avoid calling. 19ms is still reasonable.

closes #6100

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.

[alfiedotwtf]

Just curious why both range and selection_range are needed if they're the same values?

[JoshuaBatty]

Just curious why both range and selection_range are needed if they're the same values?

I just put that there as a placeholder for now, still need to sort that and quite a bit more out. Probably at least a few more days of work left to get this PR ready. I'd expect this part to change before i'm ready to open up the PR for review.

[maxtalantsev]

cool

[codspeed-hq]

CodSpeed Performance Report

Merging #6678 will degrade performances by 71.22%

_{Comparing josh/nested_outline (df451fa) with master (33d3674)}

Summary

❌ 1 regressions
✅ 21 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	master	josh/nested_outline	Change
❌	document_symbol	5.5 ms	19.1 ms	-71.22%

[alfiedotwtf]

Apart from my questions and comments, looks good!

[JoshuaBatty]

Apart from my questions and comments, looks good!

Thanks for the review. Should be good now.

[sdankel]

This looks great!

I manually tested it on a bunch of different sway files and the only issue I found is that the outline doesn't show the types for enum variants the way it does for struct fields. For example, in sway-lsp/tests/fixtures/benchmark/src/main.sw I'd expect to see u8 next to Enum11's Variant1, and so on.

[JoshuaBatty]

Good catch, adding type information in for enum fields is a great idea! I'll add that now. Thanks :)

[JoshuaBatty]

Thanks for the suggestion @sdankel , added in 552fafc

[sdankel]