PlatformMisc: add SetProcessAffinity and GetProcessAffinity #4297

Job	Run time
Linux -> Pre-checks	16s
Linux -> GCC-x64, Release	11m 54s
Linux -> Clang-x64, Release	13m 33s
Linux -> Clang-NO_GLSLANG-x64, Debug	8m 31s
Linux -> GCC-x64, Debug	12m 33s
Linux -> Clang-NO_GLSLANG-NO_HLSL-x64, Release	6m 52s
Linux -> Clang-x64, Debug	13m 43s
	1h 7m 22s

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