Fix CUIWorldMesh:GetInterpolatedAlignedBox return value

[Hdt80bro]

CUIWorldMesh:GetInterpolatedAlignedBox previously returned a table like

{
  xMin = meshInstance->xMin
  yMin = meshInstance->yMin
  zMin = meshInstance->zMin
  xMax = meshInstance->xMax
  xMax = meshInstance->yMax // bad!
  xMax = meshInstance->zMax // wrong field!
}

Now it correctly does

{
  xMin = meshInstance->xMin
  yMin = meshInstance->yMin
  zMin = meshInstance->zMin
  xMax = meshInstance->xMax
  yMax = meshInstance->yMax
  zMax = meshInstance->zMax
}