Fixed error importing .ifc that has element aggregated by ifcproject

In case if some element (not another aggregate) was aggregated by IfcProject directly, importing IFC was resulting in error below since the project's collection was never added to `self.collections`.

Traceback:
```
  File "\scripts\addons\blenderbim\bim\module\project\operator.py", line 732, in execute
    ifc_importer.execute()
  File "\scripts\addons\blenderbim\bim\import_ifc.py", line 292, in execute
    self.place_objects_in_collections()
  File "\scripts\addons\blenderbim\bim\import_ifc.py", line 1668, in place_objects_in_collections
    self.place_object_in_collection(self.file.by_id(ifc_definition_id), obj)
  File "\scripts\addons\blenderbim\bim\import_ifc.py", line 1672, in place_object_in_collection
    self.place_object_in_decomposition_collection(element, obj)
  File "\scripts\addons\blenderbim\bim\import_ifc.py", line 1689, in place_object_in_decomposition_collection
    return self.collections[aggregate.GlobalId].objects.link(obj)
KeyError: '2bKVb8E7L6e89EQYJUk8BM'
```

src/blenderbim/blenderbim/bim/import_ifc.py

@@ -1532,7 +1532,7 @@ def create_project(self):
         obj = self.create_product(self.project["ifc"])
         self.project["blender"].objects.link(obj)
         self.project["blender"].BIMCollectionProperties.obj = obj
-        obj.BIMObjectProperties.collection = self.project["blender"]
+        obj.BIMObjectProperties.collection = self.collections[project.GlobalId] = self.project["blender"]
 
     def create_collections(self):
         self.create_spatial_decomposition_collections()