The server part of #6039 

- Added support for Ground Truth jobs in a task
- Added support for job creation and removal (only Ground Truth jobs can
  be created or removed in a task)
- Added a component to autocompute quality metrics for a task
- Added tests
- Fixed https://github.com/opencv/cvat/issues/5971 (both parts - the
  outside problem and the manifest problem, the manifest part fix is also
  available in #6216)
Co-authored-by: Nklakhov <kirill.9992@gmail.com>
Co-authored-by: NRoman Donchenko <roman@cvat.ai>
Co-authored-by: NKirill Sizov <kirill.sizov@cvat.ai>