Wordpress bundles some non-essential plugins and themes, then pesters
users to upgrade them. As we make the whole webroot readonly, it is
not possible to trivially delete them. Instead we should have users
explicitly install plugins via the existing nixos module.
release-22.11 currently tracks 6.0 for pkgs.wordpress. This means there
is no way to opt in to the newer version. Similiar to nextcloud and go,
we have broken out a new derivation to opt in. It is a nop for unstable,
and only useful when backported.
Updates #208529
