Serve exported files from datastore

[fm3]

Serve exported files from the datastore (which naturally has read access to the data root dir (”binaryData”) where the exports are stored by the webknossos-worker.

New protocol:

• job result link (generated by backend) now points to datastore download route
• frontend appends a valid user token
• when the user clicks that link, the datastore
  • checks that the user may access the job export
  • fetches the job export properties
  • constructs the full file path from those
  • serves the file

TODO Frontend:

• Add datastore user token to link in list

Steps to test:

• Set up wk-worker locally
• Run a tif export job (create bbox in dataset view mode, click export icon, select layer)
• Download link in jobs list should work when job is finished, should point to datastore route (/data/* instead of /api)

Issues:

• fixes Download of exported with remote datastore #5842

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• Updated (unreleased) changelog
• Needs datastore update after deployment
• Ready for review

[jstriebel]

Nice, mostly LGTM 👍 Just two questions:

[jstriebel]