ENH: Make model slice intersection thickness control intersection poi…

…nt size as well

Models -> Display -> Slice display -> Line width now has effect when the model consists of a line.
Previously, when a line model intersected the slice the intersection point was always just 1 pixel.

Fixes issue described at https://discourse.slicer.org/t/model-linewidth/23330

Libs/MRML/DisplayableManager/vtkMRMLModelSliceDisplayableManager.cxx

@@ -625,6 +625,7 @@ ::UpdateDisplayNodePipeline(vtkMRMLDisplayNode* displayNode, const Pipeline* pip
 
   vtkProperty2D* actorProperties = actor->GetProperty();
   actorProperties->SetColor(displayNode->GetColor());
+  actorProperties->SetPointSize(displayNode->GetSliceIntersectionThickness());
   actorProperties->SetLineWidth(displayNode->GetSliceIntersectionThickness());
   actorProperties->SetOpacity(hierarchyOpacity * displayNode->GetSliceIntersectionOpacity());