Overwrite current feeds when import

[Chandler-Lu]

• [x] I have read this document: https://miniflux.app/opinionated.html#feature-request

Now, if I want to edit/delete multi feeds, it's inconvenient. I hope a feature that when I import a feed list, current feeds could be overwrite.

[gingerbeardman]

Dupe of #772 I think