Determine if a relay is eligible for a t-shirt and display on details page

A script was written for #9889 (moved) to determine if a relay is eligible for a t-shirt or not.

We've talked about having this in Atlas and having seen another mail on tor-relays today asking about eligibility, I think it's a useful feature to have.

Input from the t-shirts team would be appreciated to make sure we have the criteria correct, and to know where to send those that are eligible. Ideally we could link to a web page that explains any caveats to the process (e.g. you can't get 500 t-shirts for 500 relays) and how to apply for your t-shirt.