Add Soak modifier property

Vigor should have a property to track bonuses to Soak rolls, like the bonus to recover from Stunned or Shaken, now that DamageApplicator has built-in soaking functionality.

Furthermore, there should be a Setting option for unarmored hero that provides a +2 bonus to Soak rolls if a character does not have any armor equipped (If someone wants to have armor that "doesn't count", they can add an Active Effect to the equipped armor that applies the Soak bonus)