chore: split platform code per translation unit #47

Job	Run time
format	43s
build-windows-bazel (.bazelrc.std)	2m 27s
build-windows-cmake (arm64)	3m 22s
build-windows-cmake (amd64)	2m 49s
build-windows-bazel (.bazelrc.absl)	2m 32s
build-linux-bazel (gnu, x64, .bazelrc.absl)	1m 13s
build-linux-bazel (gnu, arm64, .bazelrc.std)	1m 12s
build-linux-bazel (llvm, arm64, .bazelrc.std)	1m 12s
build-linux-bazel (gnu, x64, .bazelrc.std)	1m 12s
build-linux-bazel (llvm, x64, .bazelrc.absl)	1m 25s
build-linux-bazel (llvm, arm64, .bazelrc.absl)	1m 13s
build-linux-cmake (gnu, arm64)	1m 49s
build-linux-bazel (llvm, x64, .bazelrc.std)	1m 23s
build-linux-cmake (gnu, x64)	2m 6s
build-linux-bazel (gnu, arm64, .bazelrc.absl)	1m 8s
build-linux-cmake (llvm, arm64)	1m 57s
build-linux-cmake (llvm, x64)	2m 32s
coverage	2m 20s
	32m 35s

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