Read only fail-over

Goal: have a regularly updated read-only fail-over copy of a production site.

For now, we use https://doc.tiki.org/Manager#instance:clone and this works, but we want to extend Tiki to have a mode that doesn't accept user input. Nor deleting (neither Tiki data nor emails in IMAP)

Making MariaDB tables read-only won't work well because Tiki will write to the DB for basic use (logs when users log in)