testresults parser does not return the executable name correctly

Currently the module coin_testresults_parser returns a field named test_executable.

• It seems it now contains the name attribute in the root XML tag <TestCase>. In my case it was opcua.
• It should contain instead the executable's name, which in my case was tst_opcua.
• The previous value could be retained and returned in its own field, for example in a "test_case" field.