K8200 y-axis pulley upgrade

This allows you to use a pulley on the y-axis instead of the bearing that comes in the k8200 kit. This is intended to be used with a GT2 belt and a 16 tooth pulley. The bearings have a tight clearance so I suggest printing at 0.2mm layer height.

This is the final version. I fixed some of the clearance issues and also enlarged the mounting holes so that you can use the bolts that came in the k8200 kit.