Fixes #918, #919 - Introduce a RoomTimelineFlowCoordinator and related FlowCoordinator protocol

Squashed commits:
Add unit tests and move the state machine into the FlowCoordinator
[bb686861] Replace the RoomFlowCoordinator's public interface with just `handleAppRoute`
[0d9a4f8d] Remove the navigationStackCoordinator dependency from the roomScreenCoordinator
[4b5fbdf2] Allow rooms to be selected from any other state
[41dbd127] Move all missing coordinators to the RoomFlowCoordinator and state machines
[f32431b7] The UserSessionFlowCoordinator does not need to conform to the CoordinatorProtocol
[0f07e87d] Fix leaving a room dismissing the currently selected one when different
[138385a2] Rewind the navigation stack when re-selecting the same room (iPad)
[0727eb93] Fix presenting different room details from the side menu on iPads
[faf4cc60] Fix selecting the same room multiple times
[fb3391da] Move room details presentation responsibility to the RoomFlowCoordinator. Fixed invitation flows.
[fa2a68d9] Rename RoomTimelineFlowCoordinator -> RoomFlowCoordinator
[0c9c06b5] Start moving things away from the RoomScreenCoordinator and into the RoomTimelineFlowCoordinator
[86cbbdcc] Introduce a RoomTimelineFlowCoordinator to deal with timeline related operations
[9b2381be] Introduce the FlowCoordinatorProtocol

ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift

@@ -154,7 +154,7 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
 
         switch action {
         case .displayMediaFile(let file, let title):
-            callback?(.displayMediaFile(file: file, title: title))
+            callback?(.displayMediaViewer(file: file, title: title))
         case .none:
             break
         }