CMake

Adapt CMakeLists to emscripten #53

Job	Run time
build (Linux-x64, DAWN, SHARED, Debug)	45s
build (Linux-x64, DAWN, SHARED, Release)	40s
build (Linux-x64, WGPU, SHARED, Debug)	36s
build (Linux-x64, WGPU, SHARED, Release)	42s
build (Linux-x64, WGPU, STATIC, Debug)	40s
build (Linux-x64, WGPU, STATIC, Release)	45s
build (Windows-MSVC-x64, DAWN, SHARED, Debug)	1m 12s
build (Windows-MSVC-x64, DAWN, SHARED, Release)	58s
build (Windows-MSVC-x64, WGPU, SHARED, Debug)	1m 22s
build (Windows-MSVC-x64, WGPU, SHARED, Release)	57s
build (Windows-MSVC-x64, WGPU, STATIC, Debug)	1m 22s
build (Windows-MSVC-x64, WGPU, STATIC, Release)	1m 26s
build (Windows-MSYS-x64, DAWN, SHARED, Debug)	1m 38s
build (Windows-MSYS-x64, DAWN, SHARED, Release)	1m 46s
build (Windows-MSYS-x64, WGPU, SHARED, Debug)	1m 42s
build (Windows-MSYS-x64, WGPU, SHARED, Release)	1m 42s
build (Windows-MSYS-x64, WGPU, STATIC, Debug)	1m 46s
build (Windows-MSYS-x64, WGPU, STATIC, Release)	1m 43s
build (MacOS-x64, DAWN, SHARED, Debug)	47s
build (MacOS-x64, DAWN, SHARED, Release)	1m 56s
build (MacOS-x64, WGPU, SHARED, Debug)	53s
build (MacOS-x64, WGPU, SHARED, Release)	1m 56s
build (MacOS-x64, WGPU, STATIC, Debug)	1m 17s
build (MacOS-x64, WGPU, STATIC, Release)	49s
build (MacOS-ARM, DAWN, SHARED, Debug)	29s
build (MacOS-ARM, DAWN, SHARED, Release)	32s
build (MacOS-ARM, WGPU, SHARED, Debug)	36s
build (MacOS-ARM, WGPU, SHARED, Release)	32s
build (MacOS-ARM, WGPU, STATIC, Debug)	32s
build (MacOS-ARM, WGPU, STATIC, Release)	32s
build (emscripten, EMSCRIPTEN, STATIC, Release, ubuntu-latest, emcmake)	3s
	32m 36s

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