feat: use pre-signed URLS for download from object storage

[kristian-zendato]

• Resolves: Use pre-signed URLs for downloading from object storage in web client #64008

Summary

Download a single file in the Files app from object storage when the server provides a pre-signed URL.
The download action requests oc:downloadURL and nc:download-url-expiration for that file only. If the URL is present and not expired, the browser fetches it directly and skips the WebDAV HEAD, because the signature is for GET. Folders, multi-file downloads, and files without a direct URL still download through remote.php/dav.
This uses the existing WebDAV properties. The storage must have direct downloads enabled (use_presigned_url on the primary object store, or Enable Direct Downloads (presigned URLs) on an external S3 mount).

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI

[pringelmann]

Seems good overall but after testing locally the downloads do not work as expected. Happy to approve though if I am missing something on my local setup.