D5907: copy: respect ui.relative-paths in copy/rename

[Yuya Nishihara]

>   `getuipathfn()` uses `repo.pathto()` when a relative path was requested (including by setting `legacyrelativevalue=True` or `forcerelativevalue=True`), so I think there shouldn't be much change in behavior with that commit.

But the default of `hg status` is `relative=False`, so the status output
would have significant change on Windows.