QmlProfiler: save trace data in background thread

Trace data is saved in the background, progress is emitted, and
the save operation can be canceled. While data is being saved
the views are disabled and a semitransparent layer is put on top
of the trace view.

Task-number: QTCREATORBUG-11822
Change-Id: I94ec93147fb1788fc85939ddc591961d058050b5
Reviewed-by: Ulf Hermann <ulf.hermann@theqtcompany.com>

src/plugins/qmlprofiler/qmlprofilertool.h

@@ -95,6 +95,7 @@ private slots:
     void showSaveOption();
     void showLoadOption();
     void showSaveDialog();
+    void onSaveFinished();
     void showLoadDialog();
 
     void toggleRecordingFeature(QAction *action);