Test parser against WebGPU's CTS parser tests

[mighdoll]

No description provided.

[mighdoll]

cc: @k2d222, we can start from your wesl-testsuite PR and adapt that... or anything more recent that you might have?

[k2d222]

I did improve the tests extraction but didn't push that just yet. I managed to extract tests expectations from the CTS without relying on Dawn. I suggest you use the current PR if you want to move forward right away, because I am travelling this week and won't be able to finish that job right now.

Also worth noting: the tests currently in PR wesl-testsuite#4 are those that match query webgpu/shader/validation/parse/*. The problem is some of these tests are not necessarily syntactic, e.g. shadowing builtins, ensuring that literals don't overflow, strict parsing of attributes. Some also could clash with WESL extensions. So while these tests are helpful to detect bugs, they would probably need to be filtered for your implementation.