Skill Checks that use different Characteristics

Add support for skill checks that may not use the default characteristic for a skill. E.g. Tradecraft or Intimidate (Fel).

My initial idea is to have extra icons next to the dice pool builder. When a dice pool is dropped onto one of these icons it swaps the Characteristic dice to the new characteristic before adding to the builder. This would make it easy to change the characteristic used for any dice pool.

Feedback from the community suggests that not everyone will want to use this feature, therefore it will require a preference to turn it on and off. Also need to ensure that it does not clutter up the UI