🐛(backend) fix dysfunctional permissions on document create

When creating a document access, users were benefitting on the targeted
document from the highest access right they have among all documents.
This is because we forgot to filter on the document ID when retrieving
the role of the user. We improved all tests to secure this issue.

src/backend/core/api/serializers.py

@@ -69,6 +69,7 @@ class BaseAccessSerializer(serializers.ModelSerializer):
             if not self.Meta.model.objects.filter(  # pylint: disable=no-member
                 Q(user=user) | Q(team__in=user.teams),
                 role__in=[models.RoleChoices.OWNER, models.RoleChoices.ADMIN],
+                **{self.Meta.resource_field_name: resource_id},  # pylint: disable=no-member
             ).exists():
                 raise exceptions.PermissionDenied(
                     "You are not allowed to manage accesses for this resource."