This used to be created here: (enabled_module.rb:50) https://github.com/opf/openproject/pull/495/files#diff-9b1389aae4dfe8f5b981510adedb10c5L50. When the wiki module gets enabled, a wikimenuitem gets initialized. The only difference to that is, that we now always have a wikimenuitem once we have a wiki, but it gets rendered selectively (menu_helper.rb:46 as of now).