Update Auto discover to be better with Nitter instances

[scottAnselmo]

Currently you have to add /rss to Nitter based feeds (e.g. https://nitter.net/EFF becomes https://nitter.net/EFF/rss) in order for News to correctly identify the feed. If you don't add /rss, even with Auto Discover, News will throw an error:

While Nextcloud users are likely to be technically savvy, the need to add /rss even w/ "Auto discover Feed" selected is likely to be not intuitive. Other RSS readers like GNOME's NewsFlash can handle discovering and adding Nitter based feeds with inputs like "https://nitter.net/EFF" without issues.

Since News has the auto discover feature, suggest updating it so that it works in correctly finding and adding Nitter feeds when /rss isn't appended.

[anoymouserver]

The auto discovery is provided by the 3rd-party dependency alexdebril/feed-io. It basically searches the html of the given url for <link> tags with a type that matches a news feed.
In case of Nitter, one is found (<link rel="alternate" type="application/rss+xml" href="/EFF/rss" title="RSS feed" />), but the url is apparently expected to contain a host (Nitter only supplies the path).

{"reqId":"EtOMSeUoxxo2wwGTI5xM","level":3,"time":"2023-05-07T20:14:57+00:00","remoteAddr":"127.0.0.1","user":"user","app":"news","method":"POST","url":"/apps/news/feeds","message":"No parser can handle this stream","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/112.0","version":"25.0.6.1","data":{"app":"news"},"id":"645806dd9e69e"}
{"reqId":"EtOMSeUoxxo2wwGTI5xM","level":2,"time":"2023-05-07T20:14:57+00:00","remoteAddr":"127.0.0.1","user":"user","app":"news","method":"POST","url":"/apps/news/feeds","message":"https://nitter.net/EFF read error : No parser can handle this stream","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/112.0","version":"25.0.6.1","data":{"app":"news"},"id":"645806dd9e68a"}
{"reqId":"EtOMSeUoxxo2wwGTI5xM","level":2,"time":"2023-05-07T20:14:57+00:00","remoteAddr":"127.0.0.1","user":"user","app":"news","method":"POST","url":"/apps/news/feeds","message":"No valid feed found at URL, attempting auto discovery","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/112.0","version":"25.0.6.1","data":{"app":"news"},"id":"645806dd9e671"}
{"reqId":"EtOMSeUoxxo2wwGTI5xM","level":2,"time":"2023-05-07T20:14:59+00:00","remoteAddr":"127.0.0.1","user":"user","app":"news","method":"POST","url":"/apps/news/feeds","message":"/EFF/rss read error : cURL error 3:  (see https://curl.haxx.se/libcurl/c/libcurl-errors.html) for /EFF/rss","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/112.0","version":"25.0.6.1","data":{"app":"news"},"id":"645806dd9e652"}