TTSD-53101

IFC export: Rebar set modifier UDAs are now exported correctly to IFC4 and IFC2x3. This now works correctly both when exporting groups (XS_EXPORT_IFC_REBARSET_INDIVIDUAL_BARS=FALSE) and individual bars (XS_EXPORT_IFC_REBARSET_INDIVIDUAL_BARS=TRUE). Previously, the exported rebars would not have any UDA values when the UDA values were exported as a property set.