refactor(index): regex updates

[Fdawgs]

• Replaced a-zA-Z0-9_ inside character class with \w word character, which is equivilent
• Replaced \u000b vertical whitespace unicode character with \v character, which is equivalent (also means the inline eslint comment can be removed as no unicode character escapes between \u0000 and \u001F are used anymore)
• Added the u unicode flag to every regex pattern, which acts as a strict mode for regex. See perf(index): convert unused capture group to non-capture group fastify-autoload#330

Master:

PR:

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct