Attack actions unsorted

With the changes to sorting as part of #205 (closed) it was revealed that the attack actions displayed on the character sheet are configured in the base Conan2d20Actor class, even though these are not used for all children of this class.

We should move these configuration steps to the ActorSheetConan2d20Character::_prepareItems() method to avoid unecessary work in the base class, and that will enable use to have the benefit of the sorting already done there.