CollectionItem: add support for filtering collections' main items.

This used to be the default, so it still is.

It only affects the list endpoint, the rest all support withCollection
anyway, because IDs are passed directly.

django_etebase/views.py

@@ -254,6 +254,10 @@ class CollectionItemViewSet(BaseViewSet):
 
     def list(self, request, collection_uid=None):
         queryset = self.get_queryset()
+
+        if not self.request.query_params.get('withCollection', False):
+            queryset = queryset.filter(parent__isnull=True)
+
         queryset, new_stoken, done = self.filter_by_stoken_and_limit(request, queryset)
 
         serializer = self.get_serializer(queryset, many=True)