Use shader's Cargo.toml for rust-gpu version/toolchain

We can still override the version and toolchain with CLI args. This
commit just changes the defaults.

I feel like there could be a lot of edge cases for this implementation.
So I consider it more of a first draft.

Notable changes:
* `Spirv` renamed to `SpirvCLI`.
* New `impl SpirvSource` that does all the shader crate querying.
* CLI args change: `--spirv-builder` is now split into
  `--spirv-builder-source` and `--spirv-builder-version`.
* `--shader-crate` now lives on the `install` subcommand, which
  because it is inherited by `build` (where it was originally), means it
  doesn't make much of a difference.
* The full build test now has a teardown function making it idempotent.
* Cache folder structure now has sub folders for `spirv-builder-cli`'s
  and `rust-gpu` repos.

Things to consider:
* Can we remove `TARGET_SPECS` now, because we have a copy of the
  `rust-gpu` repo, we can get them from there instead?
* We have to copy the `shader-crate-template` outside of the workspace
  to get the tests to run. This is because recent Cargo now uses version
  4 in `Cargo.lock` and the shader crate toolchain uses an older version
  of Cargo that doesn't recognise that version. But that doesn't seem
  right. Why is Cargo looking outside of the `shader-crate-template`
  anyway??
* What's the UX expectations for changing `spirv-std` versions or
  overriding `rust-gpu` versions and toolchain? I think in most cases
  `spirv-builder-cli` rebuilds should occur because the changes will
  cause cache directory changes. But I think it'd be good to at least
  manually test this.
* Should the main build test be moved out into an integrations tests
  folder?
* I'd still like to test each `spirv-builder-cli` feature, ie:
  `spirv-builder-pre-cli` and `spirv-builder-0_10`. We're currently only
  testing `spirv-builder-pre-cli`.

Author: tombh

.github/workflows/push.yaml

@@ -14,7 +14,10 @@ jobs:
   install-and-build-shaders:
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os:
+          - ubuntu-latest
+          - macos-latest
+          # - windows-latest
     runs-on: ${{ matrix.os }}
     defaults:
       run:
@@ -38,4 +41,4 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: moonrepo/setup-rust@v1
-      - run: cargo clippy
+      - run: cargo clippy -- --deny warnings

Cargo.lock

@@ -21,6 +21,7 @@ relative-path = "1.9.3"
 serde = { version = "1.0.214", features = ["derive"] }
 serde_json = "1.0.132"
 toml = "0.8.19"
+test-log = "0.2.16"
 
 [workspace.lints.rust]
 missing_docs = "warn"
@@ -46,7 +47,9 @@ pattern_type_mismatch = { level = "allow", priority = 1 }
 print_stdout = { level = "allow", priority = 1 }
 std_instead_of_alloc = { level = "allow", priority = 1 }
 
-# TODO: Try to not depend on these lints
+# TODO: Try to not depend on allowing these lints
 unwrap_used = { level = "allow", priority = 1 }
+get_unwrap = { level = "allow", priority = 1 }
+expect_used = { level = "allow", priority = 1 }
 panic = { level = "allow", priority = 1 }