fix: add missing connections to the abort signal

Beginning with efa3fbff39, we separated
the failing and the aborting signals, as they can mean different
things in certain contexts. Still, some places are not yet changed to
reflect this modification. This can cause aborting of progress dialogs
to not work, instead making the application hang in an unusable satte.

This goes through some places where it's not hooked up yet, fixing their
behaviour in those kinds of situation.

launcher/minecraft/MinecraftUpdate.h

@@ -27,6 +27,8 @@
 class MinecraftVersion;
 class MinecraftInstance;
 
+// FIXME: This looks very similar to a SequentialTask. Maybe we can reduce code duplications? :^)
+
 class MinecraftUpdate : public Task
 {
     Q_OBJECT