Reapply "Merge branch 'HOLI-10718_pubsub-add-fields' into 'main'"

openbook/events.py

openbook/tests/test_events.py

openbook_auth/admin.py

openbook_auth/schema/mutations.py

openbook_common/management/commands/generate_dummy_data.py

openbook_communities/admin.py

openbook_communities/events/__init__.py

openbook_communities/events/events.py

openbook_communities/events/payloads.py

openbook_communities/schema/mutations.py

openbook_communities/tests/test_events.py