fix: generate correct collection insert for object and array default values

[Aterbonus]

🔗 Linked issue

❓ 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)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

When the collection schema has an object with a default value, this object gets stringified two times instead of once.
This PR removes the JSON.stringify for default values of objects and adds code to test for correct insert code for objects and arrays.

📝 Checklist

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

[pkg-pr-new]

npm i https://pkg.pr.new/@nuxt/content@3277

commit: fa71cfc

[farnabaz]

Thanks