Initial implementation of GPUBindGroupLayout for WebGPU
Added WebIDL bindings for `GPUBindGroupLayout`, `GPUBindGroupLayoutDescriptor`, `GPUBindingType`, `GPUShaderStage` and `GPUBindGroupLayoutBinding` (Note: The servo's codegen doesn't like the name, because its already occupied).
Implemented the `createBindGroupLayout` function of `GPUDevice`.
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes addresses a part of #24706
cc @kvark @jdm @zakorgy
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