Assortment of Docs and Understandability Improvements

[cwfitzgerald]

Description

Sorry for the number of commits at once, this was a series of "let me touch that up right quick" stuff which is completely standalone and easy enough to review commit by commit.

All the hal interop stuff is made more difficult by a lack of documentation, so this is a bit of an effort to improve the docs for both as_hal and the crate in general. This was all guided by how the docs are built.

Notable changes:

• All hal interop methods in wgpu now explicitly link the corresponding hal types depending on the backend, helping navigate the sea of types.
• Removed wgpu_core::hal_api::HalApi. It wasn't really adding anything and could be easily pushed down to wgpu_hal. This vastly improves the docs output of generic functions, as they no longer link to a random trait with no docs. Also generally reduces the complexity in the wgpu world.

Squash or Rebase?

Rebase

Checklist

• Run cargo fmt.
• Run taplo format.
• Run cargo clippy --tests. If applicable, add:
  • --target wasm32-unknown-unknown
• Run cargo xtask test to run tests.
• If this contains user-facing changes, add a CHANGELOG.md entry.

[ErichDonGubler]

Putting this on a low burn for my personal pipeline, and will likely take several days on it. Here are the comments I have so far. I got up to (but not including) Add annotations for the types hal types return.

[ErichDonGubler]

I'm going to abandon a full review here, and approve. @kpreid has spent a lot of good time giving feedback, and this sort of change is very prone to conflicts. I've also failed to follow up with this, and I've not had any immediate substantive feedback with the PR, just questions about styling or how to best implement specific things.

I think it's best to merge, and iterate on any items I'd like to see fixed up. 🙂