Introduce a StartChatFlowCoordinator instead of handing a navigation stack to the Screen Coordinator. (#4674)

* Introduce a basic StartChatFlowCoordinator.

* Move the rest of the start chat flow from the screen coordinator into the flow coordinator.

* Add a UI test for the entire start chat flow.

* Refactor CreateRoom… to CreateRoomScreen…

ElementX/Sources/Screens/StartChatScreen/StartChatScreenViewModel.swift

@@ -65,7 +65,7 @@ class StartChatScreenViewModel: StartChatScreenViewModelType, StartChatScreenVie
             switch currentDirectRoom {
             case .success(.some(let roomId)):
                 hideLoadingIndicator()
-                actionsSubject.send(.showRoom(withIdentifier: roomId))
+                actionsSubject.send(.showRoom(roomID: roomId))
             case .success:
                 hideLoadingIndicator()
                 state.bindings.selectedUserToInvite = user
@@ -190,7 +190,7 @@ class StartChatScreenViewModel: StartChatScreenViewModelType, StartChatScreenVie
         switch await userSession.clientProxy.createDirectRoom(with: user.userID, expectedRoomName: user.displayName) {
         case .success(let roomId):
             analytics.trackCreatedRoom(isDM: true)
-            actionsSubject.send(.showRoom(withIdentifier: roomId))
+            actionsSubject.send(.showRoom(roomID: roomId))
         case .failure:
             displayError()
         }
@@ -205,7 +205,7 @@ class StartChatScreenViewModel: StartChatScreenViewModelType, StartChatScreenVie
     private func joinRoomByAddress() {
         if case let .addressFound(lastTestedAddress, roomID) = internalRoomAddressState,
            lastTestedAddress == state.bindings.roomAddress {
-            actionsSubject.send(.showRoom(withIdentifier: roomID))
+            actionsSubject.send(.showRoom(roomID: roomID))
         } else if let resolveAliasTask {
             // If the task is still running we wait for it to complete and we check the state again
             showLoadingIndicator(delay: .milliseconds(250))