replaced shapebuilder with general ifcopenshell code in `test_add_boolean` (the only place besides `test_shape_builder` where it was used), that way mathutils dependency in tests is localized only to `test_shape_builder.py`.
added test-safe option to makefile, so github workflow would ignore `test_shape_builder` tests for now and it wouldn't interrupt the entire workflow
added test that model.get_manual_booleans will ignore IfcBooleanClippings until we find some other solution to distinguish automatic and manual clippings. And some refactor along the way.