[Feature Request] Allow editing subscription URLs

[quentinus95]

Today, it is not possible to edit a subscription URL, we have to delete a recreate the feed.

I have some feeds that use query parameters to filter which contents I want to retrieve. I often have to tweak those parameters a lot until having the right contents in my feed.

Being able to update the URL would be useful and time saving.

[anoymouserver]

Duplicate of #873