fix: stringify protocol-relative URLs

[danielroe]

🔗 Linked issue

resolves nuxt/nuxt#25570

❓ 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

This is an attempt to fix withQuery behaviour when passed a protocol-relative URL.

withQuery('//router.com', {})
// returns `router.com`

I felt that stringifyParsedURL was the most base level fix but it does change behaviour of 'bare' hostname (seen it test). Thoughts welcome.

📝 Checklist

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

[pi0]

Thanks!