Clean up namespaces #290

Job	Run time
build (ubuntu-latest, Release)	9m 30s
build (ubuntu-latest, Debug)	9m 59s
build (macos-latest, Release)	2m 0s
build (windows-latest, Debug)	5m 23s
build (windows-latest, Release)	5m 19s
build (macos-latest, Debug)	1m 36s
publish-coverage	-1s
	33m 46s

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