refactor(firebase): update generated package.json

[pi0]

• wip
• update

🔗 Linked issue

❓ 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

Since the Nitro externals plugin is already fully aware of written dependencies, and with improvements in #1607, we can simply try to read the already written package.json and try to update it. (however, we might not the updates either in the future by adding main and engines fields by default to the generated package.json

📝 Checklist

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