fix(nuxt): add types for webpack/vite environments

[danielroe]

🔗 Linked issue

resolves #14131

❓ 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 adds asset typings and other environment types that are more precisely tailored to the builder the end user is using.

With #20748, When @nuxt/module-builder is detected, we can disable this so that our crafted types in @nuxt/schema/env can be used to prevent wrongly relying on features specific to just one of the builders (nuxt/framework#5376 (comment)).

We also avoid polluting the global context when importing from @nuxt/schema directly.

📝 Checklist

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

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[pi0]

Small nit pick: It is build(er) vs build-env. Othwrwise lgtm...