[eslint-plugin] Validate arguments of firstThatWorks

[nami8824]

What changed / motivation ?

Added validation for arguments passed to firstThatWorks() in the ESLint plugin.

Linked PR/Issues

Fixes #699

Additional Context

n/a

Pre-flight checklist

• I have read the contributing guidelines
  Contribution Guidelines
• Performed a self-review of my code

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
stylex	Skipped		Apr 17, 2026 9:21pm

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