Make it easier to unfollow (and follow) forums

[yorkshire-pudding]

To unsubscribe to a forum, you can go to the "Stop following forum" link, but that is only available at the bottom of the page when on a topic. It is not available on the topic listing page.

Also the email token replacement is not working in the emails for new topic within forum (it is working to unsubscribe from a particular topic):

[yorkshire-pudding]

See https://forum.backdropcms.org/forum/profile-problems
It would be good to be able to bulk unfollow topics somewhere.