Enhance LSP Testing Strategy for Better Reliability

[JoshuaBatty]

Description

This PR refines our testing approach for sway-lsp to ensure tests run sequentially, addressing potential async test interference. Key enhancements include:

• Implemented a run_async macro to facilitate running async tests within a synchronous environment, minimizing the boilerplate code and improving test readability.
• Updated the GitHub Actions workflow to include a dedicated job for sway-lsp, utilizing -p sway-lsp -- --test-threads=1 to enforce sequential execution of tests. This removes LSP tests from the cargo-test-workspace job.

[github-actions]

Benchmark for 8858254

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Test	Base	PR	%
code_action	5.3±0.04ms	5.3±0.17ms	0.00%
code_lens	296.0±11.13ns	292.5±10.91ns	-1.18%
compile	6.1±0.09s	6.2±0.09s	+1.64%
completion	4.9±0.07ms	5.0±0.16ms	+2.04%
did_change_with_caching	5.5±0.04s	5.7±0.11s	+3.64%
document_symbol	1059.6±8.36µs	1019.0±41.28µs	-3.83%
format	70.7±1.07ms	71.2±0.98ms	+0.71%
goto_definition	366.7±6.27µs	371.4±4.02µs	+1.28%
highlight	8.8±0.20ms	8.8±0.06ms	0.00%
hover	603.0±12.34µs	691.0±20.33µs	+14.59%
idents_at_position	122.8±0.32µs	125.3±0.54µs	+2.04%
inlay_hints	647.0±21.81µs	658.0±25.86µs	+1.70%
on_enter	492.7±29.94ns	484.3±12.98ns	-1.70%
parent_decl_at_position	3.6±0.05ms	3.6±0.04ms	0.00%
prepare_rename	363.8±5.04µs	365.2±6.80µs	+0.38%
rename	9.2±0.06ms	9.3±0.40ms	+1.09%
semantic_tokens	1014.5±13.88µs	1053.3±21.96µs	+3.82%
token_at_position	361.9±3.95µs	366.2±2.28µs	+1.19%
tokens_at_position	3.6±0.07ms	3.6±0.03ms	0.00%
tokens_for_file	417.5±1.79µs	420.1±10.13µs	+0.62%
traverse	44.8±1.95ms	45.9±1.59ms	+2.46%