Refactor: Move SyncWorkspace from Session into ServerState

[JoshuaBatty]

Description

• Moves SyncWorkspace ownership from individual Session instances to a single, global instance within ServerState.
• SyncWorkspace is now initialized once when the LSP server starts, creating a single temporary workspace clone.

Also removes the resync function. This was causing the server and the IDE to fall out of sync with each other. For example, if you have 2 panels open and then save a file in one of the tabs but have unsaved changes in the other tab then those changes would not be reflected in the temp memory folder. This meant everything would be out of sync. We already are syncing everything on each keystroke per file so this fn was not necessary in the first place.

This PR is a precursor to #7139
part of #7111

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.

[codspeed-hq]

CodSpeed Performance Report

Merging #7166 will improve performances by 16.5%

_{Comparing josh/workspace_sync (2ae531c) with master (0e3d949)}

Summary

⚡ 5 improvements
✅ 17 untouched benchmarks
🆕 1 new benchmarks

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
🆕	open_all_example_workspace_members	N/A	8.6 s	N/A
⚡	goto_definition	1.6 ms	1.4 ms	+16.05%
⚡	inlay_hints	2.2 ms	1.9 ms	+12.33%
⚡	prepare_rename	1.6 ms	1.4 ms	+16.42%
⚡	token_at_position	1.6 ms	1.4 ms	+16.5%
⚡	tokens_for_file	1.7 ms	1.4 ms	+16.31%