Deprecated `vtkm::filter::FilterField`

The original design of the filter base class required several specialized base classes to control what information was pulled from the input DataSet and provided to the derived class. Since the filter base class was redesigned, the derived classes all get a DataSet and pull their own information from it. Thus, most specialized filter base classes became unnecessary and removed.

The one substantial exception was the FilterField. This filter base class managed input and output arrays. This was kept separate from the base Filter because not all filters need the ability to select this information.

That said, this separation has not been particularly helpful. There are several other features of Filter that does not apply to all subclasses. Furthermore, there are several derived filters that are using FilterField merely to pick a single part, like selecting a coordinate system, and ignoring the rest of the abilities.

Thus, it makes more sense to deprecate FilterField and have these classes inherit directly from Filter.