New native specification for --uid

[AlessioDelConte]

Hello,

is it possible for you to add the "--uid" as native specification? I have a problem that running this from a container with user remapping, the remap is not applied also to the uid of the user that connects to the slurmctld. This generates the issue of a mismatch between users id, resulting in a UserId=nobody(997042) when submitting the job, and this cannot be executed, and keeps restarting with errors.

Thank you a lot,
Alessio