Add script to update qBittorrent peer port

[astappiev]

Inspired by #2611 and talks in #1555 created a script to update peer-port of qBittorrent.

Upd: added option to authenticate.

[AndaPlays]

I'm currently working on something similar, but I guess this would be a better solution. 👍

[astappiev]

The only downside of these scripts is that they don't cover a scenario when a client is started after gluetun.

[AndaPlays]

@astappiev Looks good to me. The only thing I would appreciate is if we could add an option for Nmap to check whether the port is actually open. I'm on a couple of private trackers, and if my TCP port is filtered, I could get heat—or in the worst case—have my account banned.

I tried integrating it into my script and controlling the VPN via the control server, but Gluetun doesn't have an API for WireGuard yet.

[astappiev]

I think it should be implemented as another script (as it is not client dependent), or even in the gluetun core.