Support getting feeds from groups.google.com #2835
Description
For example, I want to follow Firefox releases, which are on
https://groups.google.com/forum/#!forum/mozilla.announce
but FreshRSS doesn't seem to be able to translate this into
https://groups.google.com/forum/feed/mozilla.announce/msgs/rss.xml
2020-03-22 10:22:43
A feed could not be found at `https://groups.google.com/forum/#!forum/mozilla.announce`; the status code is `200` and content-type is `text/html; charset=utf-8` [https://groups.google.com/forum/#!forum/mozilla.announce]