todo: preserve file permissions with rootless containers

[wileyj]

--same-owner isn’t used on macOS because the system tar there is BSD tar, not GNU tar. BSD tar doesn’t support the --same-owner flag, and would error out if we passed it. On macOS, ownership-preservation behavior is handled automatically when running under sudo, so the extra flag isn’t needed.

BSD tar reference as used for mac os instead of GNU
BSD tar docs reference for owner

Originally posted by @ASuciuX in #29