Make PaginatedListedOriginList a concretization of PagedResult
- consistent with swh-storage and swh-indexer-storage
- we can use swh.core.api.classes.stream_results on scheduler.get_listed_origins.
Migrated from D4905 (view on Phabricator)
Staging instance, all changes can be removed at any time
Migrated from D4905 (view on Phabricator)