How to get all layers in a aseprite file?

Here's my aseprite:

There doesn't seem to be a way to get all layers in the file. When reading I only get the base layer:

```
val asp = resourcesVfs["tower_sprites.aseprite"].readImageDataContainer(ASE.toProps())

println(asp)
println(asp.imageDatas)
println(asp.imageDatasByName)

println(asp.imageDatas.first())
println(asp.imageDatas.first().frames.first())

image(asp.imageDatas.first().frames.first().bitmap) {
scaleWhileMaintainingAspect(ScalingOption.ByWidthAndHeight(300.0, 300.0))
}

```

Output of println statements:

```
com.soywiz.korim.format.ImageDataContainer@5404e08b
[ImageData([ImageFrame(BitmapSlice(null:SizeInt(width=32, height=32)), time=100ms, targetX=0, targetY=0, main=false)])]
{null=ImageData([ImageFrame(BitmapSlice(null:SizeInt(width=32, height=32)), time=100ms, targetX=0, targetY=0, main=false)])}
ImageData([ImageFrame(BitmapSlice(null:SizeInt(width=32, height=32)), time=100ms, targetX=0, targetY=0, main=false)])
ImageFrame(BitmapSlice(null:SizeInt(width=32, height=32)), time=100ms, targetX=0, targetY=0, main=false)
```

Start with the resourcesVfs["tower_sprites.aseprite"].readImageDataContainer(ASE.toProps()) call and inspect how its imageDatas and imageDatasByName results represent the file. Verify whether the Aseprite layers are being discarded during loading; done means all layers can be accessed from the returned container, with behavior covered by an appropriate test.

Written by the indexing model from the issue text.