Add an utility that calculates the screen-space position of an entity

Sometimes it would be nice to know the position in screen space of a given entity. (For simplicity, let's say, an entity's origin in model space).

At the moment this is complicated if not impossible: one has to manually track the entire entity tree of entities and combine their transformations. Animations complicate things even further, requiring communication to the frontend of their changes.

This could be solved with a convenience element that does all the magic for the user and just has a readonly property containing the desidered result. Something like

ScreenSpaceMapper {
  entity: someEntity
  camera: someCamera // or camera selector? well...
  viewport: someViewport // ditto
  
  onScreenSpacePositionChanged: console.log("new pos is", screenSpacePosition)
}

Such position could be then used to put QQ2 items overlays and so on.