root.reassign_class to handle switching occurrence class <-> type class #5260

Kind of experimental. The idea is that it will reassign class e.g. from IfcWindow to IfcWindowType (or vice versa) and will keep the IFC representations and property sets.

Example - https://imgur.com/a/X7MHR0s

src/bonsai/test/tool/test_root.py

@@ -173,7 +173,7 @@ class TestSetObjectName(NewFile):
 
 
 class TestReassignClass(NewFile):
-    def test_run(self):
+    def test_reassigning_multiple_occurrences_of_the_same_type(self):
         bpy.context.scene.BIMProjectProperties.template_file = "IFC4 Demo Template.ifc"
         bpy.ops.bim.create_project()
         ifc_file = tool.Ifc.get()