Implement QML rename functionality based on find usages

Currently you can only rename ids locally:

1. Open snake.qmlproject from Qt's sources.
2. In snake.qml, right-click on line 76:

   id: heartbeat;

   Click "Rename id heartbeat".

3. Enter a new name and click "OK".
4. Run the project.
   The game can't be started because the id was not renamed in a js file.

Creator 2.2 even finds the usage of the id in the js file but does not change it.