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

Job	Run time
check (1.60.0, windows-latest)	1m 56s
check (1.60.0, ubuntu-latest)	1m 31s
check (stable, windows-latest)	1m 5s
check (stable, ubuntu-latest)	10s
check (nightly, windows-latest)	35s
check (nightly, ubuntu-latest)	18s
	5m 35s

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