feat: support enum arg type

[Barbapapazes]

🔗 Linked issue

fix #82

❓ 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

I add support for enum. This allow to specify a list of possible values for a property and fail if the value is not in the list.

• I have a type issue with ParsedArgs. I would love to infer from the options. eg: if ['a', 'b'] are the options, then the type of the property should be 'a' | 'b' instead of string or number. I don't know how to solve it.

📝 Checklist

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