plugins should handle redirected magnet links

[de666]

Please complete the following tasks.

• Web browser cache cleared
• Link provided to install script if applicable
• Not using broken rtinst install script
• Web browser, ruTorrent, PHP and OS version provided

Tell us about your environment

Web Browser: Firefox 126.0.1
ruTorrent: v4.3.2

Tell us how you installed ruTorrent

using
https://github.com/crazy-max/docker-rtorrent-rutorrent/releases/tag/4.3.2-3.1-r0

Describe the bug

Everytime rutorrent has to add a torrent which refers to a redirected magnet URI (for example using extserach and rss plugins), it fails to add it.
Going further in details, this happens using proxies like Jackett which produces rss feeds with (not always but very often) "normal" links inside which Jackett redirects (HTTP 302) to a magnet link.

Steps to reproduce

• Add an rss feed from Jackett which doesn't have magnet link inside
• Try to download an item from that feed

Expected behavior

final (redirected) magnet link is handled correctly

Additional context

I think is due to two aspects:

1. inside the plugins (I have checkd only rss and extsearch) the magnet uri is handled before calling the fetch method (which refers to the Snoopy.php) which could handle the redirection correctly (even if it doesn't at the moment, see next point)
2. the Snoopy.php doesn't handle URIs whith scheme other than HTTP and HTTPS so if a redirection falls to a magnet URI, this is discarded returning nothing to the calling plugin