Add more dataset conversion filter
It should be simple and straightforward to convert a more structured dataset type to a less structured dataset type.
- Any to UnstructuredGrid: currently doable with AppendDataset
- Any to PolyData: ExtractSurface
- ImageData to RectilinearGrid: not doable within ParaView
- ImageData/RectilinearGrid to StructuredGrid: only RectilinearGrid to StructuredGrid can be done using RectilinearGridToPointSet filter