Blank cells are not taken into account for `vtkImageData` and `vtkRectilinearGrid` in `vtkDataSetSurfaceFilter`

Blank cells are not used when producing the external surface of vtkImageData or vtkRectilinearGrid. An algorithm producing a correct shape on regular grids is already present inside vtkDataSetSurfaceFilter, but only works on vtkStructuredGrid (see vtkDataSetSurfaceFilter::StructuredWithBlankingExecute. We can use this algorithm is we add a few missing API methods in vtkImageData and vtkRectilinearGrid that are being used in this method. Those new APIs that are required for this algorithm make sense because they have the same regular grid structure and are indexed similarly.

To reproduce:

• Load any data set that has not a rectilinear shape.
• Use vtkResampleToImageData
• Use vtkDataSetSurfaceFilter
• Visualize

Let me show how it looks like currently on some example, and how it should look like:

• Input:

• How it looks like:

• How it should look like: