This event is fired every time a check for a stage is made. This event can be canceled,
which will make the check fail.
Note: To ensure this event is reliable, all mods which add support for GameStages should
make use of
PlayerDataHandler.IStageData.hasUnlockedStage(String).
Both
net.darkhax.gamestages.capabilities.PlayerDataHandler.IStageData#hasUnlockedAnyOf(String...)
and
net.darkhax.gamestages.capabilities.PlayerDataHandler.IStageData#hasUnlockedAll(String...)
make use of this method, which makes them acceptable.