Shipping textures as PNGs is suboptimal

I've been evaluating texture compression options for including in Bevy https://bevy.org, and there's just, not really any good options?

Requirements:

* Generate mipmaps

* Convert to BC and ASTC

* Convert to ktx2 with zstd super-compression

* Handle color, normal maps, alpha masks, HDR textures, etc

* Open source

* (Nice to have) runs on the GPU to be fast

I unfortunately haven't found any option that cover all of these points. Some tools only write DDS, or don't handle ASTC, or want to use basis universal, or don't generate mipmaps, etc.

What did bevy end up using?

Nothing, I haven't found a good option yet.

We do have the existing bindings to a 2-year old version of basis universal, but I've been looking to replace it.