Function extractProperties

extractProperties(
    composed: Map<string, ComposedNode>,
    pathToId: Map<string, number>,
    strings: StringTable,
): PropertyTable
Extract properties from composed IFCX nodes.

IFCX properties are flat attributes with namespace prefixes:
- bsi::ifc::prop::IsExternal -> PropertySingleValue
- bsi::ifc::prop::Volume -> QuantitySingleValue
We group properties by namespace prefix for PropertySet-like grouping.
Parameters
- composed: Map<string, ComposedNode>
- pathToId: Map<string, number>
- strings: StringTable
Returns PropertyTable