Relay internet radio via the user's cloud instance

[paulijar]

At time being, the playback of non-HLS internet radio streams and podcasts works so that the web front-end streams the content directly from its original source. It might be beneficial to relay the internet radio feeds instead via the user's ownCloud or Nextcloud instance. Especially, this would help to solve the issue of streaming HTTP content on a cloud instance which uses HTTPS connection; at the moment this requires tweaking the page security settings on the browser.

The downside of this would be that it would cause additional load and network traffic on the server. It should be considered if this should be made a configurable feature and/or used only when streaming from a HTTP source.

Originally requested by @jacotec in #1025 (comment)

[jacotec]

I think the network traffic for audio streams is not really high on the server side ... on the pro side it would also solve geoblock issue when traveling,

[JoshuaPettus]

Unless you geoblocked your own nextcloud server for security. XD

I would support some sort of toggle. For single user or small family nextcloud instances, I don't think the added bandwidth would be too much of a great issue. We are already streaming regular music from the server. Usually these highly compressed podcast files aren't too much, and certainly better then the flac files I have. For my residential Internet, it is the server upload that is the limited resource (which I've already accepted by having a NC server), not so much download.

[JackRoublard]

Just encountered the HTTP/HTTPS mixed content issue on my small 3-user instance. I'm all in favor of this solution, provided a toggle in the admin menu which defaults to off, so as to avoid overloading traffic on big instances