AST-1020 Add getNeeds() to steps (1)
Add getNeeds() to AntennaFlagger, ApplyBeam, Averager, ColumnReader, Counter, Demixer, Filter, Interpolate, MedFlagger, MSWriter, NullStokes
Add getNeeds() to AntennaFlagger, ApplyBeam, Averager, ColumnReader, Counter, Demixer, Filter, Interpolate, MedFlagger, MSWriter, NullStokes