QmlProfiler: Move parts of model manager and trace file to Timeline

This way we can use the trace file loading and saving mechanism for
other profilers.

Change-Id: I98ec1cdde6f7abcea152cabf72e64d4e696dfa59
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/qmlprofiler/qmlprofilernotesmodel.cpp

@@ -132,6 +132,11 @@ void QmlProfilerNotesModel::setNotes(const QVector<QmlNote> &notes)
     m_notes = notes;
 }
 
+void QmlProfilerNotesModel::addNote(const QmlNote &note)
+{
+    m_notes.append(note);
+}
+
 void QmlProfilerNotesModel::clear()
 {
     TimelineNotesModel::clear();