Leave holes open in the CADSupport display mesh

This fixes a problem in the display mesh of O2BVHSurfaceSolid and adds a unit test.

- Faces with inner wires were ear-clipped from their outer wire only, so holes and pipe bores were drawn filled.
- Each hole is now bridged into the outer ring at a visible vertex before ear-clipping.
- This applies to planar, curved-planar and wire-trimmed quadric faces.
- Faces without holes keep their triangles unchanged.
- Holes that touch or cross a wire cannot be bridged, so such faces are still drawn filled.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: sawenzel