Add support for CastAndCallVariableVecField in FilterField

The FilterField class provides convenience functions for subclasses to determine the ArrayHandle type for scalar and vector fields. However, you needed to know the specific size of vectors. For filters that support an input field of any type, a new form, CastAndCallVariableVecField has been added. This calls the underlying functor with an ArrayHandleRecombineVec of the appropriate component type.

The CastAndaCallVariableVecField method also reduces the number of instances created by having a float fallback for any component type that does not satisfy the field types.