Fix Crit chance for Spells with Infusion variants (#1303)

A number of spells that use infusion variants now have a different base crit chance values that is based off of the difference between the base set, and the stat set
Fixes Ball Lightning, Firestorm, Frost Wall, Galvanic Field, Snap, Spark
Also fixes Skeletal Frost Mage's Frost Bolt skill

Co-authored-by: LocalIdentity <localidentity2@gmail.com>

Author: LocalIdentity