Add totalTimePlayed for FTBApp import

Signed-off-by: chouzz <zhouhua852@gmail.com>

launcher/modplatform/import_ftb/PackHelpers.h

@@ -36,6 +36,7 @@ struct Modpack {
     QString name;
     QString version;
     QString mcVersion;
+    int totalPlayTime;
     // not needed for instance creation
     QVariant jvmArgs;