Add torrenting port configuration support

[pcdevil]

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• I have read the contributing guideline and understand that I have made the correct modifications

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Description:

Adds TORRENTING_PORT environment variable for easy qBittorrent port change.

Benefits of this PR and context:

The torrenting port is can override qBittorrent's setting without changing the configuration. This increases the portability of the container and adds more granular control over its behaviour.

How Has This Been Tested?

1. I built the container using the command provided in the Contribution guide
2. Then I set the image in an existing docker-compose.yml to point the newly created image:

      qbittorrent:
   -     image: lscr.io/linuxserver/qbittorrent:latest
   +     image: linuxserver/qbittorrent
        hostname: qbittorrent
        volumes:
          - /media/downloads:/downloads
        ports:
          - 6887:6887
          - 6887:6887/udp
        environment:
          TORRENTING_PORT: 6887

3. Then (I waited a bit, and) I started the container and ran docker compose ps --format 'table {{.Service}}\t{{.Image}}\t{{.Status}}\t{{.Ports}}' for checking the status:

   $ docker compose  ps --format 'table {{.Service}}\t{{.Image}}\t{{.Status}}\t{{.Ports}}'
   SERVICE       IMAGE                     STATUS                   PORTS
   qbittorrent   linuxserver/qbittorrent   Up 9 minutes (healthy)   6881/tcp, 8080/tcp, 6881/udp, 0.0.0.0:6887->6887/tcp, 0.0.0.0:6887->6887/udp, :::6887->6887/tcp, :::6887->6887/udp

4. Then I also logged in via docker compose exec qbittorrent sh and checked the running command:

   root@qbittorrent:/# ps aux | grep abc
   abc          216  2.8  0.0  73636 55696 ?        Ssl  11:16   0:05 /usr/bin/qbittorrent-nox --webui-port=8080 --torrenting-port=6887
   root         399  0.0  0.0   1612     4 pts/0    S+   11:19   0:00 grep abc

5. Finally, I checked if the client's connection is active on a tracker.

Source / References:

Relates to the stale #227 pull request.

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[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/qbittorrent/4.6.3-r0-pkg-24d6d696-dev-f1b14b8d490202a869e466bdffc05f71d430c778-pr-288/index.html
https://ci-tests.linuxserver.io/lspipepr/qbittorrent/4.6.3-r0-pkg-24d6d696-dev-f1b14b8d490202a869e466bdffc05f71d430c778-pr-288/shellcheck-result.xml

Tag	Passed
amd64-4.6.3-r0-pkg-24d6d696-dev-f1b14b8d490202a869e466bdffc05f71d430c778-pr-288	✅
arm64v8-4.6.3-r0-pkg-24d6d696-dev-f1b14b8d490202a869e466bdffc05f71d430c778-pr-288	✅

[thespad]

I don't have an issue with this in principle but please remove the readme references to running without a /config mount as it's something we will not support and don't want users attempting without understanding the implications (like not persisting their torrents on an upgrade, for a start).

Will also need a matching PR for the libtorrentv1 branch.

[pcdevil]

Hey @thespad,
Thank you for looking at my pull request!

I don't have an issue with this in principle but please remove the readme references to running without a /config mount as it's something we will not support and don't want users attempting without understanding the implications (like not persisting their torrents on an upgrade, for a start).

Would you like me to re-word the description in readme-vars.yml too, or just the pull request description?

Will also need a matching PR for the libtorrentv1 branch.

Thanks for the reminder, I'll create it shortly!

[thespad]

readme-vars please.

[pcdevil]

Updated both readme-vars.yml and pull request description, see the amended e0e573c commit.

Let me know what do you think!

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/qbittorrent/4.6.3-r0-pkg-24d6d696-dev-e0e573c2480df19708ec2ba160bda5703f4c7d15-pr-288/index.html
https://ci-tests.linuxserver.io/lspipepr/qbittorrent/4.6.3-r0-pkg-24d6d696-dev-e0e573c2480df19708ec2ba160bda5703f4c7d15-pr-288/shellcheck-result.xml

Tag	Passed
amd64-4.6.3-r0-pkg-24d6d696-dev-e0e573c2480df19708ec2ba160bda5703f4c7d15-pr-288	✅
arm64v8-4.6.3-r0-pkg-24d6d696-dev-e0e573c2480df19708ec2ba160bda5703f4c7d15-pr-288	✅