I’m preparing to upgrade from Invision Community 4.7.23 to version 5. My current theme is not cool with Version 5. I read that, before attempting the conversion, I should set the theme to the IPS Default theme, but it is missing from my Themes list. The only theme available in my Admin CP is the theme I'm currently using. How can I restore or re-enable the default IPS theme so I can set it as default before upgrading?