TaskTree: Introduce CallDoneIf enum

Get rid of CustomTask c'tor taking 3 handlers.
If the done handler needs to be called only on
success or an error, add explicit 3rd arg of CallDoneIf type.

Task-number: QTCREATORBUG-29834
Change-Id: I10e55415587e6cac46620dd5177ad8269584583c
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/coreplugin/plugininstallwizard.cpp

@@ -257,8 +257,8 @@ public:
         };
 
         const Group root {
-            UnarchiverTask(onUnarchiverSetup, {}, onUnarchiverError),
-            AsyncTask<ArchiveIssue>(onCheckerSetup, onCheckerDone)
+            UnarchiverTask(onUnarchiverSetup, onUnarchiverError, CallDoneIf::Error),
+            AsyncTask<ArchiveIssue>(onCheckerSetup, onCheckerDone, CallDoneIf::Success)
         };
         m_taskTree.reset(new TaskTree(root));