Ship new HOC script(s)

replace /hoc urls with new hoc script

make new hoc, frozen, flappy and playlab "hoc-like", which means they:
- are tracked with the tracking pixels and urls
- have the aforementioned shortcut to ‘finish’ the script in the header
- when finished, redirected to /api/hour/finish (for tracking) which then redirects to the congrats page with a certificate
- certificate is the ‘Hour of Code’ certificate rather than a script specific certificate

makes new hoc and frozen not hidden
makes old hoc hidden
(mostly affects the teacher dashboard and whether scripts appear on the homepage in the progress section)