fix bug when overriding a property with bare value

the bare value must be converted to a updated property.
add also a test for this

Change-Id: I261daaaa8e12d7f739d8b2e8389c1b871b26c5b3
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/34985
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>

test/test_properties.py

@@ -148,6 +148,8 @@ def test_Property_override():
     o2 = co()
     assert o1.a == 1
     assert o2.a == 3
+    o2.setProperty('a', 4)
+    assert o2.a == 4
 
     with pytest.raises(ProgrammingError) as e:
         class cx(c):  # pylint: disable=unused-variable