Rework how the front page picks games

[connorshea]

Currently it just uses the most recently-updated games. It should use something else.

One suggestion I liked was including the top X games based on how many times the given game(s) were added to user libraries in the last 30 days. Only problem with that is how we will fill it in if there aren't enough being added to libraries in the last 30 days to reach X (though this isn't a problem in prod, only really in local dev).