feat: Add new Geometry Nodes groups for image relief and shadeless shader

- Implemented the "O Image Relief Plane" Geometry Nodes group to create a fixed-base image relief using depth images and various parameters.
- Created the "O Shadeless" shader node group to display color without scene lighting while preserving shadows and reflections.
- Introduced a preview feature for node groups, allowing for interactive visualization of node arrangements in an HTML format.
- Added a template HTML file for rendering node previews with customizable views and controls.

tests/test_preferences.py

@@ -404,6 +404,7 @@ class PreferencesTest(BlenderTestCase):
 
     def test_depth_plane_request_includes_the_global_ai_input_limit(self):
         operator = self.convert_to_plane.GenerateDepthPlane()
+        operator.plane_type = "DEPTH"
         operator.input_path = __file__
         operator.analysis_input_path = __file__
         operator.source_object_name = "Source"