Add enhanced rsr reconstruction to pygel

[cakarsubasi]

This exposes the alternative RSR reconstruction through pygel in a new module called experimental. The hierarchical reconstruction is not exposed yet although it is likely the interface will change a lot. I added hierarchical reconstruction as well although with only a minimally exposed API.

[cakarsubasi]

To test it, you can make the following change to the rsr demo project:

Subject: [PATCH] Demo change
---
Index: src/demo/RotationSystemReconstruction/rsr.py
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/demo/RotationSystemReconstruction/rsr.py b/src/demo/RotationSystemReconstruction/rsr.py
--- a/src/demo/RotationSystemReconstruction/rsr.py	(revision 85a7b0bbcaa48a1f9cfd83532df4002a41868708)
+++ b/src/demo/RotationSystemReconstruction/rsr.py	(date 1763742316306)
@@ -1,5 +1,6 @@
 from sys import argv
 from pygel3d.hmesh import rsr_recon, Manifold, save, flip_orientation
+from pygel3d.experimental.hmesh import rsr_recon
 from pygel3d import gl_display as gl
 
 def obj_load(file_path):
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