Use `OptionSet` for the granular minigame options

[EvelynTSMG]

Enhancement

So that the yaml can look better:

mini_games:
  blitzball: false
  butteflies: true
  lightning_dodging: up_to_200
  cactuar_village: false
  chocobo_training: up_to_catcher
  chocobo_race: up_to_5