Allow passing custom reference objects queryset to create_feed

changed milestone to /AlekSIS%"[NLnet #1 (closed)] Implement intelligent substitution planning"

added part::backend label

assigned to @yuha

created branch 1106-allow-passing-custom-reference-objects-queryset-to-create_feed to address this issue

mentioned in merge request !1593 (merged)

closed with merge request !1593 (merged)

mentioned in commit 12384983