NOISSUE model Task states as one enum instead of multiple flags

This adds Task::State::AbortedByUser as a possibility

api/logic/modplatform/ftb/FtbPackInstallTask.cpp

@@ -58,6 +58,7 @@ void FtbPackInstallTask::onDownloadSucceeded()
 
 void FtbPackInstallTask::onDownloadFailed(QString reason)
 {
+    abortable = false;
     emitFailed(reason);
 }