Tightening uniqueness constraints on item_ids

[ml-evs]

Pushing the discussion one step further, we should consider reinterpreting unique "ID" to mean that the same ID with dash/underscores/capitalisation is not allowed, e.g.,

jdb_2 should block JDB-2 and JdB_2. Ideally we could encode this at the MongoDB index level (I think you can do case-insensitive indexes quit readily, not sure about - vs _).

Originally posted by @ml-evs in #239 (comment)

[ml-evs]

Just ran into "." in IDs on the deployment which are now banned. There was only one item with this problem so I just casually renamed it for now. Probably also need to validate things like _____ as an ID.