Saving mouse position for every frame in online experiment

[isabelbenvenuti]

Thanks! I also needed to track time on each frame, so I ended up fixing it by adding the following to the mouse updates in the JS code:

  const position = mouse_4.getPos();
  mouse.x.push(position[0]);
  mouse.y.push(position[1]);
  mouse.time.push(mouse.mouseClock.getTime());