fix(vite, webpack): avoid generating keys where a key is already provided

[danielroe]

🔗 Linked issue

resolves nuxt/nuxt#14932

❓ 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

With webpack, we were processing code twice and therefore injecting several auto-generated keys, one after the other. This PR prevents double-insertion of keys, and also prevents insertion when there is an obvious string or template literal key provided already.

It also excludes nuxt sourcefiles (e.g. #app) from having keys inserted into them.

📝 Checklist

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

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[pi0]

I love this as workaround but also it can be even trickier in the future when we support more arguments (like 3rd options to useState) and if first arg is not a string but variable/reference. Thinking if we could change auto key injection method to be safe out of the box.

[danielroe]

You're right that we would need to update if we add more args, but the main thing it is protecting against is duplicate string keys at the end of the argument chain, which is what causes the issue.

Detecting explicit keys at the beginning is only an added benefit - not a bug fix.