Pass arguments on scene load (to intercept the loadables before they are applied to entities)

[rudderbucky]

Copying relevant discussion verbatim

Basically if I know the specific image I want to set pre-cob-load something like

LoadedUiImage{
  image:$PRELOAD_NAME
}

And then I can specify $PRELOAD_NAME when running c.ui_root().load_scene()
Cause I think a good 40% of my images are like this, 55% do not need this, and 5% are complicated enough that modifying the components directly is worth it

[UkoeHB]

Also pasted:

Right now scenes are fully extracted when files are processed. Loadables are stored as Box, so scene loading is just a bunch of T::from_reflect(). To pre-inject parameters at the load site we'd need to expand the architecture to accommodate 'parameterized nodes'.