Option to create user home if it is not present on login?

There are some cases when a user can login, have a user home directory path, but the directory itself is not present in the system. This is very common if the system is set up to use centralized auth (i.e. kerberos). Is it possible for systemdspawner to create the user home directory on login, so we don't need an admin to provision every new user manually?

Read the centralized-auth scenario in the issue, then inspect systemdspawner's login or spawn entry point to find where a missing home directory could be handled. Done means a user with a configured but absent home directory can log in and have that directory created without manual provisioning.

Written by the indexing model from the issue text.