Segmentations to 3D Slicer workflow with label names and colors

## Desired
1. Create labels with names + colors and paint segmentations in VolView.
2. Save session.volview.zip
3. Load some aspect of the session.volview.zip in 3D Slicer as segmentation
4. Expect segmentation names and colors defined in VolView to show in 3D Slicer

The reverse, Slicer to VolView:
https://github.com/Kitware/VolView/issues/530