Fix saved searces, news updates, ip bans being dumped to BigQuery.

Prevent saved searches, news updates, and ip bans from being publicly
dumped to BigQuery. They didn't override the `visible` method to
restrict their visibility for anonymous users.

app/models/ip_ban.rb

@@ -12,6 +12,14 @@ class IpBan < ApplicationRecord
     partial: 100
   }, _suffix: "ban"
 
+  def self.visible(user)
+    if user.is_moderator?
+      all
+    else
+      none
+    end
+  end
+
   def self.ip_matches(ip_addr)
     where("ip_addr >>= ?", ip_addr)
   end