Systemd sockets

**Subsystem**
Server

Systemd can create sockets (TCP, unix domain and more) for services, see https://www.freedesktop.org/software/systemd/man/systemd.socket.html
Could this be supported?
The socket doesn't disappear when the service is restarted (connections get queued) and it also helps with dependencies between services.

Start with the Server subsystem and the systemd.socket documentation linked in the issue. Define how systemd-created TCP and Unix-domain sockets would be accepted, including queued connections across service restarts and service dependencies; support for these behaviors would indicate completion.

Written by the indexing model from the issue text.