fix(seo-meta): rework meta tag mapping

[dargmuesli]

🔗 Linked issue

n/a

❓ 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

The new meta tags added in harlan-zw/zhead#18 are not prefixed with og. That way, they are not properly added to the head (see first test commit).
I observe that keys (name or property) us a custom formats:

• msapplication-TileImage
• og:audio:secure_url\

So there is no standard way to format such a key. The html standard keys seem to be all lowercase with dashes, so I kept this as standard formatting.
For all other keys, I propose to extend the MetaPackingSchema, dropping the prefix logic that's currently used e.g. for open graph tags as that logic may overlap with future keys (imagine meta information about ogres like ogre:name 😁 you get the idea).
The algorithm I implemented should work for any depth of object nesting.

Please correct me if I could make better use of packrup. It's somehow not trivial to grasp right away for my head if I could utilize that library better.

📝 Checklist

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

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Name	Status	Preview	Comments	Updated (UTC)
unjs-unhead	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 10, 2023 3:22am

[harlan-zw]

Seems good to me and if tests are passing then I think we're good.

The only downside is that we're adding some weight to the useSeoMeta composable but think that may be unavoidable, meta tags are a mess in terms of conventions.

Thanks for the hard work 👏