VTK-m now provides the following filters with the default policy
as part of the vtkm_filter library:
  - CellAverage
  - CleanGrid
  - ClipWithField
  - ClipWithImplicitFunction
  - Contour
  - ExternalFaces
  - ExtractStructured
  - PointAverage
  - Threshold
  - VectorMagnitude

By building these as a library we hope to provide faster compile
times for consumers of VTK-m when using common configurations.