message: Clean up includes.
diff: #include "CesiumEditorSettings.h"
  #include "CesiumRuntimeSettings.h"
  #include "CesiumSourceControl.h"
  -#include "Framework/Notifications/NotificationManager.h"
  -#include "HAL/PlatformFilemanager.h"
  #include "HAL/PlatformProcess.h"
  -#include "ISourceControlModule.h"
  -#include "ISourceControlProvider.h"
  #include "Misc/App.h"
  -#include "Misc/MessageDialog.h"
  -#include "SourceControlOperations.h"
  -#include "Widgets/Notifications/SNotificationList.h"
  using namespace CesiumAsync;
  using namespace CesiumIonClient;
  