Add high entropy URL to retrieve the latest high five.

Currently high-fives are stored in the database and only accessible to people that are logged in.

This new route will allow to access the information as a JSON response. However, this URL will not require being logged in, and it will only be accessible if the correct URL token is provided.

Use this exact approach for generating the URL

https://github.com/mdjnelson/moodle-mod_customcert/issues/680#issue-3028833718

Also update the README and any other places to explain our approach and justify why it is the best approach.

I do not see any built-in way inside of noodle to achieve this and so I assert this is the best approach. Please back me up by finding good publications outside of the noodle sphere explaining this type of URL entropy as a good security design.

Start by locating the existing high-five database storage and login-protected access flow, then review the README and the linked URL-entropy approach. Done means an unauthenticated JSON route for the latest high five accepts only the correct high-entropy token, with the approach and security justification documented in the README and other relevant places.

Written by the indexing model from the issue text.