Steering names are inconsistent

[haykam821]

Currently, steering names are somewhat inconsistent and do not sufficiently clarify how steering is controlled by the entity or its passenger. In particular:

• StriderEntity#canEntityControl is the same as PigEntity#canBeControlledByRider
• Entity#getPrimaryPassenger acts more like a steering passenger than a primary passenger. Even when this is null, passengers can steer the entity with their own movement. Players use this to override the movement entirely with client-side movement.

Discussion of how these names can be improved would be appreciated.