Execute docker tasks in RQ

TODO:

• Handle task failure
  • + recursive update (children tasks)
• Ponos auth (via env)
• Publish logs as artifact
• Read artifact of the parent task
• Publish artifact
• Fix existing tests
• Fix exception mentioned in !2227 (comment 224950)
• Add tests for tasks scheduler

Follow-ups:

• Support downloading and extracting ZST extra files (download_extra_files method) #1695 (closed)
• Retry single task #1696 (closed)
• Add tests for RQ agent (docker mocks) #1697 (closed)