Use the SDK's offline detection everywhere (except for restarting the sync loop). (#4472)

* Use the SDK's offline state to drive the offline indicator.

* Only use network reachability for restarting the sync loop, use the homeserver reachability for requests.

* Add a separate indicator to distinguish when the server is unreachable but the device is online.

ElementX/Sources/Screens/RoomDetailsScreen/RoomDetailsScreenViewModel.swift

@@ -49,7 +49,6 @@ class RoomDetailsScreenViewModel: RoomDetailsScreenViewModelType, RoomDetailsScr
          userIndicatorController: UserIndicatorControllerProtocol,
          notificationSettingsProxy: NotificationSettingsProxyProtocol,
          attributedStringBuilder: AttributedStringBuilderProtocol,
-         appMediator: AppMediatorProtocol,
          appSettings: AppSettings) {
         self.roomProxy = roomProxy
         self.userSession = userSession
@@ -79,7 +78,7 @@ class RoomDetailsScreenViewModel: RoomDetailsScreenViewModelType, RoomDetailsScr
             state.reportRoomEnabled = await userSession.clientProxy.isReportRoomSupported
         }
         
-        appMediator.networkMonitor.reachabilityPublisher
+        userSession.clientProxy.homeserverReachabilityPublisher
             .filter { $0 == .reachable }
             .receive(on: DispatchQueue.main)
             .sink { [weak self] _ in