webgpu: Use webgpu-native header webgpu.h instead of dawn/emscripten specific API
VTK should aim to use a C++ API on top of the common webgpu.h
C header distributed by webgpu-native repository because all implementors of webgpu use it as a baseline.
See https://github.com/eliemichel/WebGPU-Cpp/tree/main/wgpu-native. Are we better off using that or writing our own?