Make related models fields translatable

[ilya-likhota]

The aim of the PR is to translate related models fields at once with translation of root model.
Here is a use case that describe the changes:

    def test_nested_translatable_fields_queryset(self):
        firm = FirmFactory()
        profile = ProfileFactory(
            firm=firm,
            title="Title",
            translations={
                "fr_ca": {
                    "title": "FR Title",
                },
            },
        )
        person = PersonFactory(
            first_name="Jane",
            last_name="Doe",
            firm=firm,
            profile=profile,
            translations={
                "fr_ca": {
                    "first_name": "FR Jane",
                    "last_name": "FR Doe",
                },
            },
        )

        person = Person.objects.filter(id=person.id).first()
        self.assertEqual(person.first_name, "Jane")
        self.assertEqual(person.last_name, "Doe")
        self.assertEqual(person.profile.title, "Title")

        translation.activate("fr_ca")
        person = Person.objects.filter(id=person.id).first()
        self.assertEqual(person.first_name, "FR Jane")
        self.assertEqual(person.last_name, "FR Doe")
        self.assertEqual(person.profile.title, "FR Title")  # Related models fields should be translated

[hexvolt]

Does this support a chain only of 2 models? What if you have tranlatable_model.translatable_model.translatbale_model?

Or translatabale_model.regular_model.translatable_model?