feat(kit): allow vite and webpack plugins to be prepended

[danielroe]

🔗 Linked issue

https://github.com/nuxt/nuxt/pull/20367/files

❓ 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 a prepend option to addWebpackPlugin and addVitePlugin to allow plugins to be prepended to the start of the plugins list.

📝 Checklist

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

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[pi0]

About naming of option, preprend is more consistent with previous kit options we had. But also enforce: pre|past could be useful IMO since plugins adopting it.