show groups on member pages if allowed

- display groups on user pages when not the logged in user
- restrict visibility of groups on user pages and group pages themselves according to privacy settings

bookwyrm/views/user.py

@@ -83,6 +83,7 @@ class User(View):
         data = {
             "user": user,
             "is_self": is_self,
+            "has_groups": models.GroupMember.objects.filter(user=user).exists(),
             "shelves": shelf_preview,
             "shelf_count": shelves.count(),
             "activities": paginated.get_page(request.GET.get("page", 1)),