Support auto detection of unit type when adding imperial units

src/ifcopenshell-python/test/api/unit/test_add_monetary_unit.py

@@ -0,0 +1,9 @@
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestAddMonetaryUnit(test.bootstrap.IFC4):
+    def test_run(self):
+        unit = ifcopenshell.api.run("unit.add_monetary_unit", self.file, currency="USD")
+        assert unit.is_a("IfcMonetaryUnit")
+        assert unit.Currency == "USD"