classicons: Refactor and clean up code
classicons: Make sure the player has a spell that matches the element
classicons: Properly disable and hide the element if the player is in a vehicle

- This prevents the element from showing regardless if the player has the required spell or not during load
classicons: Don't show Holy Power for Paladins unless they can use it for something
classicons: Add a path and override for visibility, and document it