fix(linter): correctly handle multibyte chars in regexes

[Conaclos]

Summary

Fix #1522

Multibyte characters are now handled correctly by noMisleadingCharacterClass, noMultipleSpacesInRegularExpressionLiterals, and noEmptyCharacterClassInRegex.

noControlCharactersInRegex was not affected by the bug.

Test Plan

• New tests added.

[netlify]

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Lighthouse	1 paths audited Performance: 95 (🔴 down 4 from production) Accessibility: 97 (no change from production) Best Practices: 100 (no change from production) SEO: 93 (no change from production) PWA: - View the detailed breakdown and full score reports

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[codspeed-hq]

CodSpeed Performance Report

Merging #1592 will not alter performance

_{⚠️ No base runs were found}

_{Falling back to comparing conaclos/lint/1522 (0be7d65) with main (935bf9d)}

Summary

✅ 93 untouched benchmarks