fix(nuxt): allow overriding components + only warn if clash

[danielroe]

🔗 Linked issue

nuxt/content#2302, nuxt-themes/docus#972 (comment)

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 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 is yet another tweak to the duplicate component warning. We:

1. allow overriding components if a newly scanned component has a higher priority. No warning is needed here; this is by design. (This does result in a behaviour change but I don't think it should affect most users as we already prioritised user content over layers, and that is also what the priority system does.)
2. warn only if components are the same priority and are not layer components (which are designed to be overridden), namely have a priority of 1+

📝 Checklist

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

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