Support Private Feeds Authenticated With Http Basic Auth

[mawise]

Is your feature request related to a problem? Please describe.
I'd like to use Comma Feed to subscribe to private feeds that embed http basic auth credentials in the URL

Describe the solution you'd like
When I paste a feed URL that includes http basic auth credentials, I'd like Comma Feed to respect those credentials and give me access to the feed (I tried it on the Coma Feed demo and I got an HTTP 500 Internal Server Error). For example, this URL: https://sQi2gxaoHu:ueXNsWnajF@demo.havenweb.org/rss.

Describe alternatives you've considered
Using a different feed reader 😢

Additional context
See screenshot: