feat(cli): expose getArgs and parseArgs

[pi0]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This PR exposes getArgs and parseArgs from listhen/cli in order to help build external CLIs (such as Nitro and Nuxt) reusing shared (unjs/citty compatible) args.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[codecov]

Codecov Report

Merging #109 (3aced0b) into main (5fda128) will not change coverage.
The diff coverage is n/a.

❗ Current head 3aced0b differs from pull request most recent head d6a4795. Consider uploading reports for the commit d6a4795 to get more accurate results

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  Misses        791      791