automated direction-dependent calibration wide-field mode

Main new workflow: dd-calibration.cwl

• This workflow splits out directions with or without delay-calibration solutions applied, performs automatic calibrator selection, and runs facetselfcal on the best directions.
• Other options: pre-apply DD Dutch solutions, give alternative phasediff_score file (for deep imaging), adapt phasediff_score or peak_flux_cut in LoTSS catalogue for stricter or less strict selection
• This workflow runs split-directions.cwl and subworkflows/ddcal_calibrators.cwl

New subworkflow: ddcal_calibrators.cwl

• This launches facetselfcal for all directions, and merges the output solutions into a final multidir-h5parm

New subworkflow: auto_selfcal.cwl

• This runs facet-selfcal automatically with the option to preapply dutch solutions

Important updates to split-directions.cwl

• Step added to pre-select sources from catalogue based on their peak_flux. This step automatically converts FITS to CSV, in case FITS table is given.
• delay_solset is now an optional input parameters. This is why many of the steps required for split-directions have optional inputs. Not sure if this is the cleanest way to do this...