message: enable contact-shadows functionality in mobile gltf-viewer
  contact-shadows needs to be enabled per object.
diff: @@ -267,9 +267,14 @@ class ModelViewer(val engine: Engine) : android.view.View.OnTouchListener {
  }
  private fun populateScene(asset: FilamentAsset) {
  + val rcm = engine.renderableManager
  var count = 0
  val popRenderables = {count = asset.popRenderables(readyRenderables); count != 0}
  while (popRenderables()) {
  + for (i in 0..count-1) {
  + val ri = rcm.getInstance(readyRenderables[i])
  + rcm.setScreenSpaceContactShadows(ri, true)
  + }
  scene.addEntities(readyRenderables.take(count).toIntArray())
  }
  scene.addEntities(asset.lightEntities)
  