Rework dataset collection contents API for public histories

[mvdbeek]

The dataset collection content APIs (i.e those that deals with {history_dataset_collection_id}/contents/{dataset_collection_id}) check that the HDCA is owned by a user, but do not take into account the published status of a history. This leads to the situation where you can see the HDCA in a public history, but can't expand it until you've imported the history. There's various UX issues open that are due to this (#16048, #15917), but opening this since it is an actionable item.