Ghost cell generator for composite data sets

This introduces the new filter vtkCompositeDataSetGhostCellsGenerator, as well as new diy utilities producing ghosts: vtkDIYGhostUtilities.

vtkDIYUtilities is enhanced to automatize the linkage between blocks.

There are also a few misceallenous addings in vtkMath and vtkMatrix3x3.

The ghost cell generator filter produces ghosts between data sets of same type between ranks. In this MR, this filter works for vtkImageData and vtkRectilinearGrid. This filter heavily relies on the new diy ghost utilities, which has a generic pipeline producing ghosts. Making new data set types compatible can be done by overloading missing functions for the particular data set in these utilities, and calling the utility from the filter using the appropriate templates.