Add a way to check if a player is friends with another player

This would allow me to do things such as:

  • Reduce impact of a player’s vote during a talent show if they have a friend in the current performer pool
  • Fetch friend stats for the purposes of making an offline friends leaderboard
  • Reduce likelihood a pair of friends are both the murderer and sheriff in a murder mystery game
  • Spawn friends closer together in social or combat environments