Dynamic addon registration and orangecontrib namespace

https://gitlab.esrf.fr/workflow/ewoks/ewoksorange/-/blob/main/ewoksorange/registration.py#L85

The orangecontrib namespace does not get setup properly by register_addon_package. We currently have these qualified names of widgets:

orangecontrib.ewoks_example_supercategory.ewoks_example_subcategory.adder1.Adder1
ewoksorange.tests.examples.ewoks_example_addon.orangecontrib.ewoks_example_category.adder1.Adder1
ewoksorange.tests.examples.ewoks_example_addon.orangecontrib.evaluate.submodule.adder1.Adder1

The first one is correct but the other are not in the orangecontrib namespace.