sciencebeam judge resource requests

[de-code]

part of https://github.com/elifesciences/sciencebeam-issues/issues/135

also includes a bit of refactoring, in particular around moving utility modules out of dags, into the sciencebeam_airflow package.

resources can be specified via the container property, within the passed in evaluation and convert configuration.

e.g.

{
  "evaluation": {
    "container": {
      "requests": "..."
    }
  }
}