fix: improve data parsing for unstorage

[Aareksio]

🔗 Linked issue

https://github.com/nuxt/image/pull/1177

❓ Type of change

• [ ] 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• [x] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [ ] 👌 Enhancement (improving an existing functionality like performance)
• [x] ✨ 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

The prefix should not be required.

unstorage is not opinionated about what data type should getItem / getItemRaw return (https://github.com/unjs/unstorage/issues/142). This making creating generic wrapper a bit complicated. Since ipx requires the data to be a Buffer, I've added a simple parse attempt in order to normalize error for unsupported storages. The common return data types should be covered: ArrayBuffer, Buffer, String and Blob.

---

I also found some inconsistencies in unstorage drivers, namely http driver throws 404 when a file is not found, instead of returning null which seems to be unstorage convention. This breaks the test. I classify this as a bug in unstorage and keep the test disabled. Run TEST_UNSTORAGE_HTTP=true pnpm test to see the error.

📝 Checklist

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

Unstorage support is not documented yet

[codecov[bot]]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (39c7199) 50.73% compared to head (7df105c) 53.66%.

:exclamation: Current head 7df105c differs from pull request most recent head aefac26. Consider uploading reports for the commit aefac26 to get more accurate results

Files	Patch %	Lines
src/storage/unstorage.ts	80.00%	7 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #204 +/- ## ========================================== + Coverage 50.73% 53.66% +2.93% ========================================== Files 14 14 Lines 1157 1187 +30 Branches 48 66 +18 ========================================== + Hits 587 637 +50 + Misses 567 547 -20 Partials 3 3 ```

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[pi0]

Thanks!