TaskTree: Introduce Timeout task

By default, when finished, it returns success.
In order to convert it into failing task,
enclose it inside a Group with finishAllAndError.

Reuse it in tasking tests.

Task-number: QTCREATORBUG-28741
Change-Id: Ic81203203e0b139d4f9bfd553279ecb01cd303f4
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/libs/solutions/tasking/tasktree.h

@@ -426,6 +426,13 @@ public:
     void start() final;
 };
 
+class TASKING_EXPORT TimeoutTaskAdapter : public TaskAdapter<std::chrono::milliseconds>
+{
+public:
+    TimeoutTaskAdapter();
+    void start() final;
+};
+
 } // namespace Tasking
 
 #define TASKING_DECLARE_TASK(CustomTaskName, TaskAdapterClass)\
@@ -438,3 +445,4 @@ using CustomTaskName = CustomTask<TaskAdapterClass<Args...>>;\
 } // namespace Tasking
 
 TASKING_DECLARE_TASK(TaskTreeTask, TaskTreeTaskAdapter);
+TASKING_DECLARE_TASK(TimeoutTask, TimeoutTaskAdapter);