feat(test-utils): test in development mode

[pi0]

🔗 Linked issue

Rework of #3693

❓ 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

Allow testing nuxt build in development mode:

• Add new dev option to test utils
• Support --dev and --watch to nuxi test
• Add new isDev() utility from @nuxt/test-utils to check if testing in development environment
• Directly use nitro server listener
• (prod) Inherit stdio for process

To be improved: Wating for loading is via a loop to fetch and check payload. We could improve state management (hooks are unreliable for this since both nitro and vite need to be done) (~> #730)

Try: yarn nuxi test examples/with-test --dev

📝 Checklist

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

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