[YoutubeBridge] Cache RSS feed URL resolution (#5081)* [YoutubeBridge] Cache RSS feed URL resolutionCache RSS feed URL and icon URL when using custom name with no duration.RSS URLs for channels shouldn't change, so they can be cached for a long time.* [YoutubeBridge] Only cache RSS data on successful resolutionCaching without any checks could lead to a single failed attemptblocking future feed access, until cached data expires.