Add initial pre-processing step
This MR creates an initial pre-processing CWL step, copying the basic functionality of the old pre-processing pipeline.
This minimal step includes the following steps and inputs:
- Flagging (with AOFlagger): set by the flagging strategy.
- Demixing: given a list of sources, frequency steps, time steps.
- Averaging: frequency steps, time steps.
- Dysco compression
Additionally, it adds a default flagging strategy, sky model, and example step input.
Edited by Mick Veldhuis