mod actions: fix messages to use consistent format.

Fix mod actions to use the same message format everywhere.

Before mod actions were formatted in various inconsistent ways:

* "deleted post #1234"
* "comment #1234 updated by <user>"
* "<user> updated forum #1234"
* "<user> level changed Member -> Builder"

Now all mod actions consistently use this format:

* "deleted post #1234"
* "updated comment #1234"
* "updated forum #1234"
* "promoted <user> from Member to Builder"

This way mod actions are formatted consistently with other actions on
the /user_actions page, where everything is written as "<user> did X".

Also add a fix script to fix existing mod actions.

app/models/ip_ban.rb

@@ -52,11 +52,11 @@ class IpBan < ApplicationRecord
 
   def create_mod_action
     if new_record?
-      ModAction.log("#{creator.name} created ip ban for #{ip_addr}", :ip_ban_create)
+      ModAction.log("created ip ban for #{ip_addr}", :ip_ban_create, creator)
     elsif is_deleted? == true && is_deleted_was == false
-      ModAction.log("#{CurrentUser.user.name} deleted ip ban for #{ip_addr}", :ip_ban_delete)
+      ModAction.log("deleted ip ban for #{ip_addr}", :ip_ban_delete)
     elsif is_deleted? == false && is_deleted_was == true
-      ModAction.log("#{CurrentUser.user.name} undeleted ip ban for #{ip_addr}", :ip_ban_undelete)
+      ModAction.log("undeleted ip ban for #{ip_addr}", :ip_ban_undelete)
     end
   end