Add comprehensive tests for image processing nodes and refactor node imports

- Introduced new test files for image layer, image plane, normal scale, object normal rotation, shadeless, and temporary attributes.
- Implemented tests to validate the behavior of alpha curves, depth layers, and normal scales in various rendering engines.
- Refactored import paths for node groups to align with the new directory structure.
- Added checks for temporary attribute lifetimes and ensured proper cleanup without warnings.
- Enhanced CLI commands to require the Blender group and validate the presence of generated node assets before packaging.
- Updated packaging scripts to enforce the existence of necessary assets, preventing build failures.

nodes/common/validity.py

@@ -0,0 +1,10 @@
+"""Delete the faces the depth mask excludes."""
+
+
+def delete_invalid_faces(group, geometry, invalid):
+    nodes, links = group.nodes, group.links
+    delete = nodes.new("GeometryNodeDeleteGeometry")
+    delete.domain, delete.mode = "FACE", "ALL"
+    links.new(geometry, delete.inputs["Geometry"])
+    links.new(invalid, delete.inputs["Selection"])
+    return delete.outputs["Geometry"]