Add API endpoint for downloading a single job artifact

What does this MR do?

This MR adds a new endpoint to the API, that makes it possible to download a single job artifact file.

Does this MR meet the acceptance criteria?

• Changelog entry added,
• Documentation created/updated
• API support added
• Tests added for this feature
• Has been reviewed by Backend

What are the relevant issue numbers?

Closes #37196 (closed)