JSON feed support

[ghost]

Checklist

• [x] I checked, but didn't find any duplicates (open OR closed) of this issue in the repo.
• [x] This issue contains only one feature request. I will open one issue for every feature I want to request.

What feature do you want?

I want to be able to follow json feeds within the app

Why do you want this feature?

JSON feeds are structured in a more readable way than atom or rss which can lead to it being less prone to human error when writing. Here is a JSON feed you could test with if you want to implement this.

[bubelov]

In most cases, this app is not responsible for parsing feeds. It can try to parse feeds only in experimental standalone mode. In case of the standalone mode, the parsing is done by feedk. Transferring this issue to its repo.