fix many implicit ifcopenshell.guid imports

a bit related to 10d30b0de

src/ifctester/test/ids_doc_generator.py

@@ -23,6 +23,7 @@ import pytest
 import functools
 import ifcopenshell
 import ifcopenshell.api
+import ifcopenshell.guid
 import ifctester
 import test_facet
 import test_ids

src/ifctester/test/test_facet.py

@@ -20,6 +20,7 @@
 import uuid
 import ifcopenshell
 import ifcopenshell.api
+import ifcopenshell.guid
 import ifctester.facet
 from ifctester.facet import Entity, Attribute, Classification, Property, PartOf, Material, Restriction