API: Add user online stats

[gl1tchdev]

hey
see XTLS/Xray-core#3637.
user stats api has been updated in xray core 24.11.5 - ip counter config added.
can u add ip limit per email and display counter it in admin panel? or at least add api to work with this stat through rest api

[gl1tchdev]

if someone needs temporary solution:

1. marzban core-update
2. update config:

  "policy": {
    "levels": {
      "0": {
        "statsUserOnline": true
      }
    },
    "system": {}
  }

docker exec marzban-marzban-1 /var/lib/marzban/xray-core/xray api statsonline -s 127.0.0.1:34728 --email={id}.{email}
where id - marzban db user id, and email - true username.
but I started to think that access.log more useful for limit connections.

I hope this feature will appear at marzban api and good luck :)

[M03ED]

Done on next branch.