extensions/khr: Add VK_KHR_pipeline_binary extension

[MarijnS95]

No description provided.

[MarijnS95]

Our no_std build complains:

error[E0412]: cannot find type `Vec` in this scope
  --> ash/src/extensions/khr/pipeline_binary.rs:66:19
   |
66 |     ) -> VkResult<Vec<u8>> {
   |                   ^^^ not found in this scope
   |
help: consider importing this struct
   |
3  | use alloc::vec::Vec;
   |

It's quite unfortunate that the clippy::std_instead_of_alloc lint didn't warn that Vec from the prelude is in std (this lint only triggers if use std::vec::Vec is explicitly imported). CC @i509VCB who landed this feature, I haven't found an upstream tracking issue but maybe you know about this?

[Ralith]

Not really a blocker, but I'd like to see some sort of reference for why we think 4KiB in particular makes sense here rather than, say, 128B, or 1MiB.

[Ralith]

Vec::reserve takes the number of additional bytes, so this will over-allocate. We should pass count - data.capacity() (probably via a temporary to keep borrowck happy).

[Ralith]

nit: We don't expect to reallocate this any further, so Vec::reserve_exact would be a little better.