Conversation view should show preview cards (if configured)

[nikclayton]

Working on another refactoring I've noticed that if "Show link previews in timelines" is enabled link previews are not shown in conversations.

The conversation object from the server has the necessary info, but it's never extracted in to a ConversationStatusEntity, so it's not available to display.

Wholly unclear why the behaviour is like that (except that it matches the behaviour of the webapp).

Also not clear why ConversationStatusEntity exists as a distinct type. From the API docs it's a regular Status, and if that was used then the preview card would be available.