Add NOTIFY_SOCKET to get notify from runc

[futurist]

What happened?

conmonrs server DOESN'T receive notification from runc notify socket from file:
https://github.com/opencontainers/runc/blob/main/notify_socket.go

What did you expect to happen?

conmonrs server NEED receive notification from runc notify socket from file:
https://github.com/opencontainers/runc/blob/main/notify_socket.go

NEED to receive signals like READY, MAINPID, and ExitCode, OOM etc.

How can we reproduce it (as minimally and precisely as possible)?

run conmonrs server, then create a runc instance using go client normally.

Anything else we need to know?

Podman have sdnotify option:

https://docs.podman.io/en/latest/markdown/options/sdnotify.html

conmon-rs version

$ conmonrs --version
# paste output here

version: 0.5.1
tag: none
commit: b90bcd665b5d5b48d925a4c7413e24de295333d3
build: 2023-04-24 06:48:10 +00:00
target: x86_64-unknown-linux-gnu
rustc 1.69.0 (84c898d65 2023-04-16)
cargo 1.69.0 (6e9a83356 2023-04-12)

OS version

# On Linux:
$ cat /etc/os-release
# paste output here

PRETTY_NAME="Debian GNU/Linux 9 (stretch)"
NAME="Debian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
VERSION_CODENAME=stretch
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

$ uname -a
# paste output here

Linux n227-026-119 4.19.117.bsk.6-amd64 #4.19.117.bsk.6 SMP Debian 4.19.117.bsk.6 Mon Jan 4 07:25:51 UTC x86_64 GNU/Linux

Additional environment details (AWS, VirtualBox, physical, etc.)

physical