Add 1-component ({s,u}{int,norm}{8,16}, float16) and unorm8x4-bgra vertex formats

[nolanderc]

Connections
Closes #6614

Description

When adding the translations from wgpu::VertexFormat to the various backends, I did my best to choose the appropriate formats, but I'm not too familiar with DX12 or Metal, so please, take some extra time to verify those.

Testing
N/A

Checklist

• Run cargo fmt.
• Run taplo format.
• Run cargo clippy. If applicable, add:
  • --target wasm32-unknown-unknown
  • --target wasm32-unknown-emscripten
• Run cargo xtask test to run tests.
• Add change to CHANGELOG.md. See simple instructions inside file.

[cwfitzgerald]

As I have a big change coming in that conflicts with this, I'm going to rebase so each commit can land separately.

[cwfitzgerald]

Ah wait, hold on, metal is a lot more complicated unfortunately, as we don't use normal vertex formats, we manually transform to using vertex pulling.

First step is that I would add tests for all these new formats in https://github.com/gfx-rs/wgpu/blob/e23146aa3e8f5de0820cec108a9c1aa967454a3b/tests/tests/vertex_formats/mod.rs. This can probably join one of the other sets of tests.

Second step is to add support for these formats in naga -

wgpu/naga/src/back/msl/writer.rs

Line 4002 in 314e196

fn write_unpacking_function(

. If you need mac testing help or any support, please let us know on the wgpu dev matrix in the readme.

I would appreciate the webgpu update as a separate PR, as this has a bit of work left still.

[nolanderc]

This should now be good to go @cwfitzgerald @ErichDonGubler