Fix follow/unfollow buttons on public profile (fixes #7036) (#7040)

* Fix follow/unfollow buttons on public profile

- Present non-logged users with web+mastodon:// URLs for remote accounts
- Present logged-in users with appropriate links (authorize_follows and
  remote_unfollows) for remote accounts

* Do not cache rendered cards if user is logged in

app/views/accounts/_follow_grid.html.haml

@@ -2,6 +2,6 @@
   - if accounts.empty?
     = render partial: 'accounts/nothing_here'
   - else
-    = render partial: 'accounts/grid_card', collection: accounts, as: :account, cached: true
+    = render partial: 'accounts/grid_card', collection: accounts, as: :account, cached: !user_signed_in?
 
 = paginate follows