[naga-cli] Add input-kind and shader-stage args

[ratmice]

Connections
None

Description
When dealing with .glsl files which have just a plain .glsl extension in git.
Renaming things such that they include the shader stage can be inconvenient.

This adds an argument --shader-stage and uses the FromStr implementation of that for both extension parsing and command line arguments.

This also allows fragment, vertex, compute to be accepted as well.

In addition this also adds --input-kind argument which accepts glsl, etc...

🍀

Testing

touch foo{,{,.{bar,frag,fragment}}.glsl}
cargo run -p naga-cli -- foo.frag.glsl
cargo run -p naga-cli -- --shader-stage frag foo.glsl
cargo run -p naga-cli -- --shader-stage frag --input-kind glsl foo
cargo run -p naga-cli -- foo.fragment.glsl
# should error
cargo run -p naga-cli -- foo.bar.glsl
cargo run -p naga-cli -- --shader-stage bar foo.glsl

Checklist

• Run cargo fmt.
• 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]

This is definitely needed functionality! Have some comments about errors and code structure.

[ratmice]

@cwfitzgerald I believe I have resolved all of your review concerns.

This leaves on the table some additional clean-ups regarding existing errors, and replacing them with anyhow usage.
I figured these should be left for a follow up patch.

[cwfitzgerald]

Waiting for anyhow is fine, though it may just be easier to switch without needing to build out the anyhow-like infra. Up to you.

Requesting changes as some changes weren't made.

(Reminder: please re-request a review from me once the changes are addressed to make sure I see it!)

[ratmice]

Sorry about the branch mixup, this switches it to use anyhow, and should contain the fixes I was referring to previously.

What i'd meant previously is that there are further cleanups to existing code that can probably benefit from using anyhow.
But this patch just does the minimal changes needed for the new code to use context() etc. With the intent to do those cleanups in a follow-up.

[cwfitzgerald]

Looking a lot better, one more round, then just need a naga person to sign off on it, then we're good to land!

[cwfitzgerald]

Great - going to boop the naga people

[teoxoy]

Nice!