Create a new theme for Moodle.org and related Moodle based community sites

A new theme is needed to server Moodle.org and other sites like demo.moodle.org and downloads.moodle.org

The theme will be a child theme of both theme Boost and theme Classic

Basic requirements are:

• provide bootswatches for each domain
• keep navigation similar to the current moodle.org theme
• review all css and update / remove legacy css
• review all custom plugins used on the domains and make sure they work with the new theme (create separate issues for these if possible)
• rewrite all custom widgets to use modern renderers / templates