WebGPU: Fix geometry buffer renderer in WebGPU

[Popov72]

In WebGPU (WGSL), if you declare some uniforms in the shader code (even if you don't use those uniforms in the code itself) the drawing code must set their values and can't leave them empty.

So, the declarations must be guarded by some #ifdef to make sure the uniforms we don't set values for are not declared in the shader code.

[azure-pipelines]

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[azure-pipelines]

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