Fixes #18900: raise QuerySetNotOrdered exception when trying to paginate unordered API querysets (#19943)

* Fixes #18900: introduce/raise QuerySetNotOrdered exception

Defines a new exception, `QuerySetNotOrdered`, and raises it in
`OptionalLimitOffsetPagination.paginate_queryset` in the right
conditions:
- the iterable to be paginated is a QuerySet isinstance
- the `queryset.ordered` flag is not truthy

* Don't try to reapply ordering if ordering is already present

* Add ordering for failing tagged-objects list API endpoint

I chose to implement this here for TaggedItemViewSet, rather than on the
model, because any meaningful ordering is going to be done on the
related Tag instance and I didn't want to introduce potential, not well
understood side-effects by applying a model-wide ordering via a related
model field.

* Add default Token ordering behavior

* Adds basic tests for raising QuerySetNotOrdered

* Note why ordering is not applied in TaggedItem.Meta

netbox/users/models/tokens.py

@@ -74,6 +74,7 @@ class Token(models.Model):
     class Meta:
         verbose_name = _('token')
         verbose_name_plural = _('tokens')
+        ordering = ('-created',)
 
     def __str__(self):
         return self.key if settings.ALLOW_TOKEN_RETRIEVAL else self.partial