no-std support in naga

[brody4hire]

Connections

issue(s):

• this should be the first step in terms of no-std support as requested in issue: Support no_std where possible (specifically for wasm32v1-none) #6826

recommended pre-requisite(s):

• use hashbrown in naga, etc - PR: use hashbrown in naga & main wgpu crates, etc. #6938

blocking other proposal(s):

• support no-std in wgpu-core - PR no-std support in wgpu-core #6926

Description

I think this should be the beginning of adding no-std support to the wgpu crates.

This proposal enables build & usage of naga with no_std. New "std" option is added & enabled by default.

All existing options require "std" feature to build. TODO item is to support as many features as possible with no-std. I may want to defer these updates to a future PR.

There are quite a few loose ends, mostly marked by XXX todo comments, I hope to make some progress resolving these over the weekend.

/cc @bushrat011899

Testing

• cargo test --no-default-features -p naga
• cargo test --all-features -p naga
• cargo xtask test

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.
• Resolve any possible issues in CI.
• Resolve or defer remaining XXX todo items in these updates.