[Feature Request] - Add a second alternative url to server

[enrikotero]

Summary

The server data now only allow one url but sometimes it's very useful to have an url for external connection and (if it falls) an alternative one for local connection.

Use Case

I use a different server url when I'm in my local network connected to the home wifi that the server url I use when I'm away from home idiom my smartphone data. I know I can create now 2 different server connections but it's not optimal because I'm not really connecting to a different server, it's just the same one.

Additional context

Other apps (like substreamer and symfonium) already included this option.

[CappielloAntonio]

I implemented the feature recently and it's the only thing I have left to test thoroughly before making a release of the new version. It's a nice feature, but I wouldn't want to harm those who are using the app happily at the moment