fix: simplify abort handling and add missing emits

Signed-off-by: flow <flowlnlnln@gmail.com>

launcher/modplatform/atlauncher/ATLPackInstallTask.h

@@ -93,6 +93,7 @@ protected:
 private slots:
     void onDownloadSucceeded();
     void onDownloadFailed(QString reason);
+    void onDownloadAborted();
 
     void onModsDownloaded();
     void onModsExtracted();