Track inner adventure levels in the database

[Toastbrot236]

This could be a way to both implement #927 and make adventures more interesting on the API/website, where users would be able to view all levels inside an adventure with their respective scores and photos. The inner levels could probably be tracked with the GameLevels table, where they would be able to reference the level ID of the adventure they belong to, and their own inner ID, which LBP3 includes when uploading an adventure. They would also have to be hidden from all level category queries.