Improve compute shader validation error message

[haraldreingruber]

Checklist

• Run cargo clippy.
• Run RUSTFLAGS=--cfg=web_sys_unstable_apis cargo clippy --target wasm32-unknown-unknown if applicable.
• Add change to CHANGELOG.md. See simple instructions inside file.

Connections
Potential improvement for #2985

Description
The previous error message was easily misunderstood, as it didn't say explicitly that each dimension and the total number must be below the bounds.

For example, instead of:

shader entry point current workgroup size [8, 8, 8] must be less or equal to [256, 256, 64] of total 256

after applying this PR the error is:

shader entry point current workgroup size [8, 8, 8] of total 512 must be less or equal to [256, 256, 64] and of total 256

Thanks to @mwalczyk for the original improvement idea 🙏

Testing
In shader.wgsl of the hello-compute example, I've changed the @workgroup_size(1) to @workgroup_size(8, 8, 8)

[cwfitzgerald]

Thank you! Suggested some alternative wording to help make the error message even more clear.

[codecov-commenter]

Codecov Report

Merging #3139 (0ec0e65) into master (d1ff383) will increase coverage by 63.42%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           master    #3139       +/-   ##
===========================================
+ Coverage    1.34%   64.76%   +63.42%     
===========================================
  Files          70       81       +11     
  Lines       18683    38764    +20081     
===========================================
+ Hits          251    25106    +24855     
+ Misses      18432    13658     -4774     

Impacted Files	Coverage Δ
wgpu-core/src/validation.rs	58.87% <0.00%> (+58.87%)	⬆️
wgpu-hal/src/empty.rs	0.00% <0.00%> (ø)
wgpu-core/src/present.rs	0.00% <0.00%> (ø)
wgpu/src/util/encoder.rs	0.00% <0.00%> (ø)
wgpu-hal/src/dx11/device.rs	0.00% <0.00%> (ø)
wgpu/examples/framework.rs
wgpu-hal/src/metal/mod.rs
wgpu/examples/cube/main.rs
deno_webgpu/src/error.rs
wgpu/tests/common/mod.rs
... and 83 more

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[cwfitzgerald]

Thanks!