List experiments for the analytics picker

Every experiment in the environment with just its groups, for the query builder's breakdown and filter picker. Unpaginated and changeset-free: the picker renders one flat list and needs only names, so paging the list endpoint and then fetching each experiment's detail would be N+1 for data it discards. Includes ended and terminated experiments — their markers are still queryable — with state so the UI can de-emphasise them, and unitType because a server experiment's bins count player events rather than servers.