system: Introduce Kueue as an optional alternative approach how to submit user jobs

[xaviertintin]

This pull request introduces changes to the reana-job-controller component to enable Kueue as an optional job submission method in REANA, working in conjunction with the previously submitted changes to reana-workflow-controller.

Key Changes:

1. Environment Variable Access:

• Retrieves the KUEUE_ENABLED environment variable within reana-job-controller/reana_job_controller/config.py. This variable reflects the admin's selection of Kueue during deployment via Helm values.

2. Deployment Type Selection:

• Based on the retrieved environment variable, the code in reana-job-controller/reana_job_controller/kubernetes_job_manager.py dynamically selects the appropriate job submission method:
  • Standard: If KUEUE_ENABLED is False, the existing Kubernetes Job API is used for job submission.
  • Kueue: If KUEUE_ENABLED is True, the pull request implements the necessary logic to utilize Kueue for job submission.

Benefits:

• Aligns reana-job-controller with the changes in reana-workflow-controller to enable Kueue as an optional job submission method.
• Ensures that the chosen job submission approach (standard or Kueue) is reflected in the actual job execution handled by reana-job-controller.