Ownership of samba/public and samba/private is not correct, or rather is not mapping correctly

[astromechza]

https://github.com/AstromechZA/dockerized_home_server/blob/master/samba/Dockerfile#L31

It might have been some side effect of stuff done outside the container, but the shares came up with incorrect user/group infos: everything was owned by root:root. The translation of uid:gid then gets messed up when viewed from outside the container.

Best thing would be able to have matching uid and gid inside and outside the container. Maybe passing the uid/gid in from outside would work? Need a sambagroup group, sambapublic user, and sambaprivate user. The start script in the container will chmod the dirs/files on start up to make everthing the expected values. Then on the host it all works out well too.
Pass through uid/gid by integer value so that we adapt the names.