feat/unit factory test

[nikophil]

Here are some test backported from Unit\FactoryTest which were creating errors with foundry 2.x code

FactoryTest

• [x] can_register_custom_faker()
• [x] can_use_arrays_for_attribute_values()
• [x] can_register_default_instantiator()
• [x] instantiating_with_proxy_attribute_normalizes_to_underlying_object()
• [x] instantiating_with_factory_attribute_instantiates_the_factory()
• [x] ~can_create_object()~ not useful test in 2.x
• [x] ~can_add_after_persist_events()~ After persist event should not be called in unit test (?)