* Rename PaginationState.timelineEndReached to PaginationState.endReached.
* Rename PaginationState to TimelinePaginationState.
Also renames PaginationStatus to PaginationState so that a TimelinePaginationState consists of the forward and backward pagination states.
* Add the empty state to SpaceScreen.
Only has 1 of the 2 buttons for now.
* Add the timeline controller factory to the timeline view model.
In preparation for building a timeline to swipe through media in QuickLook.
* Refactor RoomTimelineControllerFactory.
* Refactor RoomTimelineController.
* Refactor RoomTimelineProvider.