Release ash 0.38.0 and ash-window 0.13.0

[MarijnS95]

This is a head-start with a "little" migration guide explaining all the breaking changes we've done over the past two (!!) years, to be posted in the GitHub release (and I'm not sure if it should reside in the keepachangelog file). Please let me know if there's anything breaking or otherwise important that deserves a mention.

[Ralith]

Did you want to reword the #894 changelog entry to make more sense in isolation?

[MarijnS95]

Did you want to reword the #894 changelog entry to make more sense in isolation?

Good catch! I removed the flattened `ash::vk::*` extension modules into `ash::vk`, bit and added , and moved high-level extension wrappers from `ash::extensions::*` to `ash::<prefix>::<extension name>::{Instance, Device}` to #734.