fix(das): return all errors from RedundantStorageService

[davidjsonn]

When multiple inner storage services failed, RedundantStorageService was only returning the last error, silently discarding all previous ones. This made debugging really hard because you'd only see one failure even if three services were down for different reasons.

Changed GetByHash, Put, Sync, and Close methods to collect all errors into a slice and return them via errors.Join(). Now when something goes wrong, you actually get the full picture of what failed.

[github-actions]

Thank you for your contribution. However, this PR has been automatically closed because it was labeled as trivial. As stated in our CONTRIBUTING.md:

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