GaudiKernel: migrate tests to pytest and various fixes
Migrate the GaudiKernel python tests from nose to pytest (they were already running as pytest but with several deprecation warnings).
In addition extend test_Configurables
to cover more use-cases (in preparation for !1503 (merged)):
- Fix the cleanup function
- Extend the test to
dict
andlist
properties - Migrate to
pytest
fixtures and exception handling