Fix export linked file using api

[mostafa901]

This fix is targeting exporting Linked Revit files via Revit Api. not through the UI,
The implementation was already set but very coupled to the UI, I separated the export code, and placed it in another IFCLinkDocumentExporter. We may change the name " I don't like long ones"

usage via API is straight forward:

Document doc = uidoc.Document;
View view = uidoc.ActiveGraphicalView;
IFCExportOptions ifcOptions = new IFCExportOptions();

IFCExportConfiguration configExporter= IFCExportConfiguration.CreateDefaultConfiguration();
configExporter.IFCVersion = IFCVersion.IFC2x3;
configExporter.UseActiveViewGeometry = true;
configExporter.UpdateOptions(ifcOptions, view.Id);

configExporter.ExportLinkedFiles = LinkedFileExportAs.ExportSameProject;
doc.Export(@"d:\", "IFC_TestSampleFile", ifcOptions);

// if separated
configExporter.ExportLinkedFiles = LinkedFileExportAs.ExportAsSeparate;
configExporter.LinkExporter.ExportSeparateDocuments(@"d:\IFC_TestSampleFile"); 

This is tested over Revit 2025
I have also made a workaround sample till this is merged over here

[denizmaral]

Thank you very much for that! I also struggled to export it via API. In Revit 2024 we shelved that functionality because we did not have much time to find a solution. I hope your pull request will be accepted and will be released soon.

FYI: @andydandy74

[o-babii]

Hi @mostafa901 ,

Thank you for this submission and detailed description, we will look into your approach and consider implementing this fix.

Regards,
Oleksandr