insofar we have an `occupant_id`.
We do this by subclassing `create` on the `ChatRoomOccupants` collection
and `save` on the `ChatRoomOccupant` model, to make sure that whenever
an occupant is created or saved, that the `id` matches the `occupant_id`
value if it's available.
This lets us look up the occupant via `occupant_id` via dictionary lookup,
instead of array traversal.
Another change is to save `from_real_jid` when adding an occupant to a message
- Clear timer when a messages changes from epehemeral to non-ephemeral
- Set MUC occupant on `groupchat` message when `type` changes to `groupchat` (from `error`)
- Set roster contact on `chat` message when `type` changes to `chat` (from `error`)
Thanks @afriedmanGlacier
This let's us populate the `from_real_jid` attribute for messages in
cases where the user's nickname has changed.
Only save the occupant-id if the MUC supports it
Store all advertised features on the `chatbox.features` model.
This allows us to look up a feature without using the async
`disco.supports` API.
Updates #2241
