multi-user systemd support

[gtirloni]

Is your feature request related to a problem? Please describe.

Support for multiple-user in the systemd flavor of Fedora Remix

Describe the solution you'd like
Ability to continue using systemd with non-standard users (e.g. added through useradd).

Describe alternatives you've considered
None

Additional context
If you try to use any systemd commands through your secondary user in WSL, it'll fail:

$ id
uid=1001(user2) gid=1001(user2) groups=1001(user2),993(docker)

$ systemctl daemon-reload
==== AUTHENTICATING FOR org.freedesktop.systemd1.reload-daemon ====
Authentication is required to reload the systemd state.
Authenticating as: default
Password:
==== AUTHENTICATION COMPLETE ====

$ systemctl enable --user ssh-agent.service
Failed to connect to bus: No medium found

[crramirez]

Hello @gtirloni,

Looks like a good addition. We are going to discuss it internally to see how much effort it requires.

Regards,
Carlos