Implement RPS Attacks

- When a player plays Rock, Paper, or Scissors, attack players to either side.
- An RPS attack fails if the "blocking" card was played by the target.
- Otherwise, the target loses 10 health.

TODO: Resolve cards by some priority.

Clean up
Add priorities to cards

- Sort players by card priority before applying card effects
- Moving happens before attacks (and other stuff happens very first)