LSP Optimization: Remove ParseResult and write to session types directly

[JoshuaBatty]

Description

We no longer write TokenMap or Metrics into an intermediate copy and then back to the original in write_parse_result. Instead, we write to them directly during traversal if the compilation was successful.

related to #5445

Metric	Before	After	Change (%)
traverse & write	122.018ms	74.353ms	-39.07%

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).
• 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.