feat: support loading files from npm packages

[markbrockhoff]

🔗 Linked issue

Related: #2999

❓ 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

As proposed in #2999, I created a basic implementation for loading translation files form npm packages.
This gives more flexibility in reusing and distributing translations. The feature should be especially useful for module / library authors wanting to provide translations which can be used to integrate with @nuxtjs/i18n.

📝 Checklist

• I have linked an issue or discussion.
• I have added tests (if possible).
• I have updated the documentation accordingly.