Function extractTypePropertiesOnDemand

Extract type-level properties for a single entity ON-DEMAND. Finds the element's type via IfcRelDefinesByType, then extracts property sets from:

1. The type entity's HasPropertySets attribute (IFC2X3/IFC4: index 5 on IfcTypeObject)
2. The onDemandPropertyMap for the type entity (IFC4 IFCRELDEFINESBYPROPERTIES → type) Returns null if no type relationship exists.