function isLayerShapeGroup(layer) {
  return (
    layer.isKindOfClass(MSShapeGroup.class()) ||
    layer.isKindOfClass(MSRectangleShape.class()) ||
    layer.isKindOfClass(MSTriangleShape.class()) ||
    layer.isKindOfClass(MSOvalShape.class()) ||
    layer.isKindOfClass(MSStarShape.class()) ||
    layer.isKindOfClass(MSPolygonShape.class())
  )
}
Checks if the layer is a shape/shape group.

@param {MSLayer} layer
@returns {Boolean}