Fixes to translucent Rendering
Try to fix some issues show in #17404 (closed) as well as other transparency issues with vtkCompositePolyDataMapper2
Previously mappers could only report GetIsOpaque which would render them as opaque or transparent. With this change mappers can report if they have TranslucentPolygonalGeometry as well as OpaqueGeometry and they can report both. If they report both they will get invoked on both passes. This allows complex mapperssuch as CPDM2 to do render some blocks during the opaque pass and other blocks during the translucent pass.
Create better logic in vtkScalarsToColors to report If the scalar mapping would produce translucent results and use that logic in a couple places where it had been duplicated.