Updates EffEquip, CondIsWearing, and adds CondIsSaddled

[cheeezburga]

This PR originally was to only update the equip effect, but now does all the following:

• General updates to the equip effect (horse and steerable stuff)
• Adds wolf support to the equip effect
• Updates the equip test (now tests with armour, horses, wolves)
• Adds saddled condition, to test if a valid entity is saddled
• Adds saddled test
• Updates CondIsWearing to check for an item in the BODY slot of an entity as well

This resolves #6838