Add keybinds for zooming in and out for multi-zoom scopes

For scopes that have more than 2 zoom levels - it would be really nice to have separate keybinds to be able to zoom in and out rather than having to cycle through all zoom levels one at a time. For example, binding the mouse wheel to zoom in/out would be so much easier than going from zoom 1, 2, 3, 4 just to get back to zoom 1 again.