This adds the possibility to use the `gpu_BaryCoord[NoPersp]`
builtin to support barycentric coordinates without geometry shader.
The `BuiltinBits::LAYER` builtin needs to be manually added
to the `GPUShaderCreateInfo` in order to use this feature.
Note: This is only available for shaders using `GPUShaderCreateInfo`.
A geometry shader fallback is generated if the extension
`AMD_shader_explicit_vertex_parameter` is not available.
`NV_fragment_shader_barycentric` was not considered because it is not
present inside the `glew.h` with use and seems to only be available
with vulkan.
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