Allow us to rebind "toggle scope" key - currently hard coded to F key.

Not only do we need a toggle scope key but it also needs to work when not scoped in. It is super problematic only being able to change your scope zoom when you're *fully* zoomed in. If you zoom and press F too quickly it will melee instead. There is nothing more annoying than getting a looooooong melee animation just because you wanted to switch to close combat zoom level and then get shot because you're stuck in the melee animation.