Add `OsString` support to `windows-registry` crate #199

Job	Run time
check (1.70.0, windows-latest)	28s
check (1.70.0, ubuntu-latest)	15s
check (stable, windows-latest)	1m 8s
check (stable, ubuntu-latest)	9s
check (nightly, windows-latest)	27s
check (nightly, ubuntu-latest)	14s
	2m 41s

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