Function buildHierarchy

buildHierarchy(
composed: Map<string, ComposedNode>,
pathToId: Map<string, number>,
): SpatialHierarchy
Build spatial hierarchy from composed IFCX nodes.

IFCX hierarchy comes from children relationships:
- Project -> Site -> Building -> Storey -> Elements
We identify spatial structure elements by their bsi::ifc::class codes.
Parameters
- composed: Map<string, ComposedNode>
- pathToId: Map<string, number>
Returns SpatialHierarchy