Open and Closed State for Copper Grates

Since we already have plenty of blocks that can be waterlogged without flowing, the copper grate doesn't stand out much right now.

When exposed to a redstone pulse, similarly to copper bulbs, grates could change their state; the default "open" state we're familiar with, and a new "closed" state. The open grates would have water flow from all sides, however, while the closed grate functions as the grate currently does. This would be the first omnidirectional flow toggle, as opposed to trap doors or doors that can only toggle two faces.

If the idea of fluid/item passthrough gets implemented, this would be a great way to enhance the functionality of that as well.