feat: add fuzzy_match helpers and tests

[SaaiAravindhRaja]

External (non-OpenAI) Pull Request Requirements

This pull request adds two new helper functions to the codex-rs/common/src/fuzzy_match.rs module, making it easier to check for fuzzy matches and retrieve match scores. It also introduces corresponding unit tests to ensure these helpers work correctly.

Fuzzy matching helpers:

• Added fuzzy_matches, a convenience function that returns true if needle fuzzy-matches haystack (codex-rs/common/src/fuzzy_match.rs)
• Added fuzzy_score, a function that returns the fuzzy match score if a match exists, or None otherwise (codex-rs/common/src/fuzzy_match.rs)

Testing:

• Added unit tests for the new fuzzy_matches and fuzzy_score helper functions to validate their behavior (codex-rs/common/src/fuzzy_match.rs)

[github-actions]

All contributors have signed the CLA ✍️ ✅
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[SaaiAravindhRaja]

I have read the CLA Document and I hereby sign the CLA

[bolinfest]

I feel like this is trivial for anyone to add this helper functions who is using this externally. Since we aren't using it ourselves in the Codex CLI codebase and we are not publishing these crates for external use, I am not going to take this change. It would like get deleted as unused code at some point on our side, anyway.