[Feature] Segmentation Support for Deformable Materials

[ACMLCZH]

1. Segmentation maps now include deformable materials such as FEM, MPM, PBD, and SPH.

• When colorize_seg=False, the segmentation output is a 2D array of integer indices.
• Use camera.get_segmentation_idx_dict() to retrieve the mapping from indices to scene elements:
  • $0$ → background (entity_id = -1)
  • $>0$ → scene elements, represented as (depending on the material type and segmentation level.):
    • entity_id
    • (entity_id, link_id)
    • (entity_id, link_id, geom_id)

2. Double-Sided Surface Support for Segmentation Rendering.
3. Unit Tests for Segmentation Rendering.

Resolves /issues/1072
Resolves /issues/1194

[duburcqa]

I fixed your PR. I will push directly on it!

[duburcqa]

Failing on Windows. I will investigate.

[ACMLCZH]

You can close #1194