Notes: -This lets system designers specify arbitrary values for attributes. They can be based on any formula they want. -Projects with very large level caps may wish to take a simpler "Attributes gained per level" approach. -Anything initialized in this method should not be directly modified by gameplay effects. E.g., if MaxMoveSpeed scales with level, anything else that modifies MaxMoveSpeed should do so with a non-instant GameplayEffect. -"Default" is currently the hardcoded, fallback GroupName. If InitAttributeSetDefaults is called without a valid GroupName, we will fallback to default.