getent
This adds `setpwent()`, `getpwent_r()`, `endpwent()`, `setgrent()`, `getgrent_r()`, and `endgrent()` interfaces to nss-systemd library. Thus, dynamic users can be enumerated by e.g. `getent passwd` command.
With this NSS module all dynamic service users will be resolvable via NSS like any real user.