build: upgrade rust to v1.84.0

[unvalley]

Summary

This PR upgrades rust (v1.84.0), fixes clippy errors and format.
Since I'd like to do the clippy fixes in the next branch, the direction was set as the next branch.

Test Plan

[codspeed-hq]

CodSpeed Performance Report

Merging #4910 will improve performances by ×140,000

_{Comparing unvalley:rust-1.84.0 (080246c) with next (4f07cc8)}

Summary

⚡ 11 improvements
✅ 84 untouched benchmarks

Benchmarks breakdown

	Benchmark	next	unvalley:rust-1.84.0	Change
⚡	css_analyzer[bootstrap_18416142857265205439.css]	216,151.4 µs	4.5 µs	×48,000
⚡	css_analyzer[bulma_5641719244145477318.css]	617,441.6 µs	4.5 µs	×140,000
⚡	css_analyzer[foundation_11602414662825430680.css]	147,265.7 µs	4.5 µs	×33,000
⚡	css_analyzer[tachyons_11778168428173736564.css]	120,465.4 µs	4.5 µs	×27,000
⚡	js_analyzer[css_16118272471217147034.js]	18,918 µs	35.3 µs	×540
⚡	js_analyzer[index_3894593175024091846.js]	45,888.8 µs	35.4 µs	×1,300
⚡	js_analyzer[lint_13640784270757307929.ts]	35,534.5 µs	38.3 µs	×930
⚡	js_analyzer[parser_13571644119461115204.ts]	65,636.3 µs	35.4 µs	×1,900
⚡	js_analyzer[router_17129688031671448157.ts]	19,122.8 µs	35.3 µs	×540
⚡	js_analyzer[statement_263793315104667298.ts]	60,859.6 µs	35.3 µs	×1,700
⚡	js_analyzer[typescript_3735799142832611563.ts]	98,719.8 µs	35.3 µs	×2,800