Provide computational steering in ParaView/Live.
Allow vtkCPInputDataDescription grids to be marked as steering parameters (i.e., they hold no visualization data but are instead a table naming field-data arrays used to steer the simulation). When connecting live, ask the simulation to provide steering parameters by default. Do not make the user add them; the user may enable/disable them by calling `coprocessor.EnableSteering(True/False)` as desired. When they exist, create "pipeline producers" for them so they appear in the pipeline browser. This adds a new SI class for named properties used by the steering parameters, which are properties added to a self-generating source subclass. See `Documentation/release/dev/catalyst-steering.md` for more information.