Add regex option in the search filter's context menu

In the search job widget.

src/gui/search/searchjobwidget.h

@@ -96,6 +96,7 @@ private:
     void saveSettings() const;
     void updateFilter();
     void filterSearchResults(const QString &name);
+    void showFilterContextMenu(const QPoint &);
     void displayToggleColumnsMenu(const QPoint&);
     void onItemDoubleClicked(const QModelIndex &index);
     void searchFinished(bool cancelled);