Add compute shader for converting cells to lower dimension primitives
requested to merge jaswant.panchumarti/vtk:add-compute-shader-for-cell-to-primitive-conversions into master
This MR also enables the usage of webgpu compute pipelines with Metal/D3D12. Since a render window override is unnecessary, adjust the CMake code to permit building the module when there is no override for webgpu render window on mac/windows.
Edited by Jaswant Panchumarti (Kitware)