Add frontend-control for configuring parallel execution in backend

This issue is to plan the frontend-integration of the backend's parallel execution features (#27 (closed), !98 (merged)).

Proposal

  • Provide CLI arguments to manually enable/disable parallel execution
  • Consider providing information about whether parallel execution is available to the frontend
  • For sweeps, allow to decide whether there should be parallel execution in the backend or frontend-parallelisation
    • This could be made dependent on the number of WorkerManager worker tasks configured
  • Evaluate what needs to be done for ~"cluster support"