TaskTree: Make it possible to invoke done handler only with DoneResult

Remove unused "const Task &" argument from done handlers.

Task-number: QTCREATORBUG-29834
Change-Id: I0e69c1eba88d9fdb78de7ba1705ff3916999dc89
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/diffeditor/diffeditorplugin.cpp

@@ -110,7 +110,7 @@ DiffFilesController::DiffFilesController(IDocument *document)
 
     const TreeStorage<QList<std::optional<FileData>>> storage;
 
-    const auto setupTree = [this, storage](TaskTree &taskTree) {
+    const auto onTreeSetup = [this, storage](TaskTree &taskTree) {
         QList<std::optional<FileData>> *outputList = storage.activeStorage();
 
         const QList<ReloadInput> inputList = reloadInputList();
@@ -147,7 +147,7 @@ DiffFilesController::DiffFilesController(IDocument *document)
 
     const Group root = {
         Storage(storage),
-        TaskTreeTask(setupTree),
+        TaskTreeTask(onTreeSetup),
         onGroupDone(onTreeDone),
         onGroupError(onTreeError)
     };