refactor(biome_js_parser/syntax): use enumflags2 for ModifierFlag

[Javimtib92]

Summary

Part of #3157

Adds enumflags2 to biome_js_parser ModifierFlag

Test Plan

I ran cargo t on the root and all tests passed. Current CI should pass

[codspeed-hq]

CodSpeed Performance Report

Merging #3796 will improve performances by 6.03%

_{Comparing Javimtib92:refactor/js-parser-syntax-modifier-flag-enum (b17fa0a) with main (bcad101)}

Summary

⚡ 1 improvements
✅ 106 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	Javimtib92:refactor/js-parser-syntax-modifier-flag-enum	Change
⚡	db_17847247775464589309.json[uncached]	16.2 ms	15.3 ms	+6.03%