Link.Create fails when file owner is an empty string

[e9gille]

In an unusual scenario, starting a docker container within a GItHub runner, the owner of the files that are accessed is a user not defined within the current docker container. When using 5 ⎕NINFO file it returns an empty string. Link tries to set the attributes of the function and fails with a length error. See: https://github.com/Dyalog/link/blob/9f6ab1ddf411cd1517ad50ef566baa51f0297fe1/StartupSession/Link/Utils.apln#L834