Update player readiness and game configuration

The 'all_players_ready' field was moved from 'state_representation.py' to 'game_server.py'. Instead of being part of the initial state of the game, it's now part of the server environment, making it easier to keep track of the readiness of all players. Additionally, the game configuration in 'study_config.yaml' was updated to accommodate one player instead of two and no bots.