PR: Roofs with inserts not exported as aggregations in IFC4 RVArch

### Problem Description

When a roof contains an inserted object (e.g. an opening) it is exported as a singular ```IfcRoof``` element, not as an aggregation that contains an ```IfcSlab``` element. Since this didn't happen in IFC2x3 CV2 (and still doesn't) I am curious whether this is by design or should be treated as a bug? It would be great to have the same behaviour (export as aggregation) here in both cases - e.g. the nested ```IfcSlab``` provides better base quantities.

Minimal model to reproduce: https://github.com/andydandy74/MyIssues/blob/master/RevitIFC652/134_IFC_RoofNotAggregated.rvt


### Revit Version

2023.1.x

### IFC for Revit Addon Version

23.3.0

### Windows Version

10 22H2

Start with the linked minimal Revit model and compare its IFC4 RVArch export with the IFC2x3 CV2 export, focusing on how a roof containing an inserted object is represented. Done means the IFC4 RVArch case exports as an aggregation containing an IfcSlab, matching the requested behavior and preserving the relevant base quantities.

Written by the indexing model from the issue text.