ui: Refactored context menu API, added file path actions in graph and code

* Add 'copy full path' and 'show containing folder' actions to graph view, code view
* Added file path to file node tooltip

bug id = 320

src/lib_gui/qt/window/QtMainWindow.cpp

@@ -272,7 +272,8 @@ void QtMainWindow::keyPressEvent(QKeyEvent* event)
 
 void QtMainWindow::contextMenuEvent(QContextMenuEvent* event)
 {
-	QtContextMenu::getInstance()->showDefault(event, this);
+	QtContextMenu menu(event, this);
+	menu.show();
 }
 
 void QtMainWindow::closeEvent(QCloseEvent* event)