Move useradd command to fates-specific dockerfiles? about fates-containers

[glemieux]

Noting that the baseos files have had the useradd removed per #11, but hlm dockerfiles still need to be updated and migrated in.

[glemieux]

Do we actually need to have a specific user for the build process? On a related note, I think we should be using docker run --user $(id -u):$(id -g) call to make sure that when we volume mount the input and output files, the user and group ids are automatically handled as described here: https://vsupalov.com/docker-shared-permissions/

[glemieux]

Closed per #26. Note that cime needs a user environment variable, but does not need to be called from a /home/$USER directory. In fact, the Dockerfile should actually be built with the root user since passing --user $(id -u):$(id -g) will only match the calling user ids if the container base permission for the volume mounting targets is root.