Fixed texture array multisampling validation

[inner-daemons]

Connections
Closes #8565

Description
Here the spec discusses validation of multisample state for textures. It says the following:

["1d"](https://www.w3.org/TR/webgpu/#dom-gputexturedimension-1d)

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[width](https://www.w3.org/TR/webgpu/#gpuextent3d-width) must be ≤ limits.[maxTextureDimension1D](https://www.w3.org/TR/webgpu/#dom-supported-limits-maxtexturedimension1d).

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[height](https://www.w3.org/TR/webgpu/#gpuextent3d-height) must be 1.

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[depthOrArrayLayers](https://www.w3.org/TR/webgpu/#gpuextent3d-depthorarraylayers) must be 1.

        descriptor.[sampleCount](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-samplecount) must be 1.

        descriptor.[format](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-format) must not be a [compressed format](https://www.w3.org/TR/webgpu/#compressed-format) or [depth-or-stencil format](https://www.w3.org/TR/webgpu/#depth-or-stencil-format).

["2d"](https://www.w3.org/TR/webgpu/#dom-gputexturedimension-2d)

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[width](https://www.w3.org/TR/webgpu/#gpuextent3d-width) must be ≤ limits.[maxTextureDimension2D](https://www.w3.org/TR/webgpu/#dom-supported-limits-maxtexturedimension2d).

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[height](https://www.w3.org/TR/webgpu/#gpuextent3d-height) must be ≤ limits.[maxTextureDimension2D](https://www.w3.org/TR/webgpu/#dom-supported-limits-maxtexturedimension2d).

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[depthOrArrayLayers](https://www.w3.org/TR/webgpu/#gpuextent3d-depthorarraylayers) must be ≤ limits.[maxTextureArrayLayers](https://www.w3.org/TR/webgpu/#dom-supported-limits-maxtexturearraylayers).

["3d"](https://www.w3.org/TR/webgpu/#dom-gputexturedimension-3d)

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[width](https://www.w3.org/TR/webgpu/#gpuextent3d-width) must be ≤ limits.[maxTextureDimension3D](https://www.w3.org/TR/webgpu/#dom-supported-limits-maxtexturedimension3d).

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[height](https://www.w3.org/TR/webgpu/#gpuextent3d-height) must be ≤ limits.[maxTextureDimension3D](https://www.w3.org/TR/webgpu/#dom-supported-limits-maxtexturedimension3d).

        descriptor.[size](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-size).[depthOrArrayLayers](https://www.w3.org/TR/webgpu/#gpuextent3d-depthorarraylayers) must be ≤ limits.[maxTextureDimension3D](https://www.w3.org/TR/webgpu/#dom-supported-limits-maxtexturedimension3d).

        descriptor.[sampleCount](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-samplecount) must be 1.

        descriptor.[format](https://www.w3.org/TR/webgpu/#dom-gputexturedescriptor-format) must support ["3d"](https://www.w3.org/TR/webgpu/#dom-gputexturedimension-3d) textures according to [§ 26.1 Texture Format Capabilities](https://www.w3.org/TR/webgpu/#texture-format-caps).

Clearly, this disallows multisampling for 1D and 3D textures but allows it for 2D textures and 2D texture arrays. The existing validation only checked that an image with multisampling >1 had an array length or depth of 1. This incorrectly allowed 1D textures and 3D textures with depth 1 to have multisampling, and incorrectly blocked 2D texture arrays.

Testing
Nothing new

Squash or Rebase?
Squash

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.

[andyleiserson]

Might be worth a changelog mention.

[andyleiserson]

Maybe InvalidMultisampledDimension to align with existing InvalidMultisampled* and Invalid*Dimension.

[inner-daemons]

Done

[andyleiserson]

It seems like the CTS (webgpu:api,validation,createTexture:sample_count,1d_2d_array_3d:*) does not think multisampled array textures are valid.

Running that test locally, I also got an assertion failure in Metal. It looks like the wgpu-hal metal backend does not map the texture type properly for the array multisampled case.

[andyleiserson]

incorrectly allowed ... 3D textures with depth 1 to have multisampling

This actually is not allowed by the code, because there are redundant checks related to multisampling. Depth-1 3D multisampled textures are disallowed in check_texture_dimension_size.

(I do think that redundant checks are bad because they result in exactly this kind of confusion, I filed #8568 about that.)

[inner-daemons]

@andyleiserson Thanks for the feedback. This might be more controversial than I assumed in that case, so maybe push it off until the next meeting or discuss further in the issue linked.