Index operator using Index trait

[xunilrj]

Description

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.

[github-actions]

Benchmark for a0cad0f

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Test	Base	PR	%
code_action	5.0±0.14ms	5.0±0.13ms	0.00%
code_lens	291.7±9.73ns	326.9±11.92ns	+12.07%
compile	2.5±0.06s	2.5±0.02s	0.00%
completion	4.5±0.11ms	4.6±0.09ms	+2.22%
did_change_with_caching	2.5±0.03s	2.4±0.03s	-4.00%
document_symbol	904.7±28.57µs	912.8±52.36µs	+0.90%
format	70.6±1.49ms	69.4±1.56ms	-1.70%
goto_definition	336.8±8.47µs	346.8±8.88µs	+2.97%
highlight	8.7±0.21ms	8.9±0.24ms	+2.30%
hover	476.7±14.31µs	522.3±14.81µs	+9.57%
idents_at_position	117.2±2.38µs	116.3±2.82µs	-0.77%
inlay_hints	612.6±19.34µs	621.7±27.13µs	+1.49%
on_enter	2.0±0.08µs	2.0±0.07µs	0.00%
parent_decl_at_position	3.6±0.08ms	3.5±0.11ms	-2.78%
prepare_rename	332.7±7.97µs	336.4±8.06µs	+1.11%
rename	9.0±0.19ms	9.3±0.09ms	+3.33%
semantic_tokens	1226.9±35.08µs	1171.5±34.65µs	-4.52%
token_at_position	330.9±7.05µs	321.6±7.02µs	-2.81%
tokens_at_position	3.6±0.08ms	3.5±0.08ms	-2.78%
tokens_for_file	396.1±14.66µs	391.9±8.09µs	-1.06%
traverse	36.0±0.57ms	36.3±1.03ms	+0.83%

[github-actions]

Benchmark for 5ffbe4f

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Test	Base	PR	%
code_action	5.2±0.09ms	5.2±0.05ms	0.00%
code_lens	286.3±8.99ns	284.6±5.32ns	-0.59%
compile	2.7±0.05s	2.7±0.03s	0.00%
completion	4.7±0.02ms	4.7±0.19ms	0.00%
did_change_with_caching	2.6±0.04s	2.6±0.07s	0.00%
document_symbol	912.6±37.98µs	856.8±20.45µs	-6.11%
format	72.2±0.57ms	72.9±1.15ms	+0.97%
goto_definition	334.4±9.50µs	339.0±7.83µs	+1.38%
highlight	9.0±0.08ms	8.9±0.15ms	-1.11%
hover	494.7±6.91µs	490.8±6.47µs	-0.79%
idents_at_position	130.7±0.57µs	129.0±0.74µs	-1.30%
inlay_hints	634.6±11.41µs	639.5±30.26µs	+0.77%
on_enter	2.1±0.06µs	2.0±0.02µs	-4.76%
parent_decl_at_position	3.7±0.02ms	3.7±0.04ms	0.00%
prepare_rename	325.7±8.81µs	340.9±7.67µs	+4.67%
rename	9.3±0.11ms	9.2±0.02ms	-1.08%
semantic_tokens	1210.1±12.20µs	1217.9±10.54µs	+0.64%
token_at_position	335.1±4.85µs	341.5±2.26µs	+1.91%
tokens_at_position	3.7±0.02ms	3.7±0.02ms	0.00%
tokens_for_file	402.7±2.91µs	396.3±2.67µs	-1.59%
traverse	37.2±1.15ms	38.1±0.94ms	+2.42%

[github-actions]

Benchmark for 4ad9685

Click to view benchmark

Test	Base	PR	%
code_action	5.2±0.07ms	5.1±0.07ms	-1.92%
code_lens	284.9±6.52ns	292.8±8.99ns	+2.77%
compile	2.6±0.05s	2.7±0.04s	+3.85%
completion	4.7±0.02ms	4.5±0.08ms	-4.26%
did_change_with_caching	2.5±0.04s	2.6±0.03s	+4.00%
document_symbol	892.1±42.49µs	931.7±28.11µs	+4.44%
format	72.3±0.94ms	72.7±0.65ms	+0.55%
goto_definition	336.3±2.46µs	341.9±5.67µs	+1.67%
highlight	9.0±0.06ms	8.6±0.05ms	-4.44%
hover	487.7±4.08µs	496.8±7.84µs	+1.87%
idents_at_position	121.1±0.25µs	120.6±0.79µs	-0.41%
inlay_hints	640.7±13.18µs	631.1±12.46µs	-1.50%
on_enter	2.0±0.06µs	2.1±0.04µs	+5.00%
parent_decl_at_position	3.7±0.02ms	3.5±0.02ms	-5.41%
prepare_rename	339.6±9.64µs	341.4±8.33µs	+0.53%
rename	9.3±0.14ms	8.9±0.09ms	-4.30%
semantic_tokens	1260.5±9.47µs	1214.5±13.07µs	-3.65%
token_at_position	367.2±1.80µs	340.7±1.39µs	-7.22%
tokens_at_position	3.7±0.02ms	3.5±0.01ms	-5.41%
tokens_for_file	401.0±5.93µs	429.9±3.48µs	+7.21%
traverse	36.2±1.12ms	37.2±1.01ms	+2.76%