Remove duplicate points in vtkDataSetSurfaceFilter for VTK_BEZIER_CURVE
If a curve is composed, for instance, of two linear VTK_BEZIER_CURVE, the vtkDataSetSurfaceFilter previously created 4 points (the point between the two elements was duplicated). This behavior differs from other linear cell types (e.g., VTK_LINE, VTK_LAGRANGE_CURVE, etc.).
This commit fixes the issue with VTK_BEZIER_CURVE by detecting if a point has already been processed, instead of systematically creating new points.
This fix the difference of behavior observed in paraview/paraview#22617 between VTK_BEZIER_CURVE
and VTK_LAGRANGE_CURVE
( but it of course does not fix the issue that the GhostCellGenerator filter do not work with duplicated points).