Happy Ghast rework

I want to share an idea to improve the Happy Ghast. Right now, it's really hard to control because it constantly drifts away. When you use snowballs to guide it, it flies way too far into the distance, and the moment you dismount, it just flies off unpredictably. It would be great if it stayed closer to the player. Also, it would be much smoother if we could hold snowballs in our off-hand while controlling it, so we don't have to constantly fiddle with the hotbar. Finally, the AI needs a fix when towing something: currently, if you attach a boat to the Ghast, the lead either snaps, or the Ghast flies into walls and suffocates the passenger/mob sitting inside the boat. The Ghast should behave much calmer when something is attached to it.