Added camera zoom

[Icodextrin]

Features implemented:

optional zoom (zoom_enable)
zoom toggle or zoom hold
adjustable zoom multiplier (1x, 2x, etc.)
optional automatic mouse sensitivity adjustment such that the zoomed view keeps the same sensitivity as unzoomed

Needed a camera zoom for an immersive sim and came up with this. Made it a bit more flexible so it would fit with other fps type uses.

[CZakarya]

I see that you have zooming as a state. This is an interesting way to implement camera zoom. This would prevent players from sprinting or crouching while the camera is zoomed in. I can understand why you may want to prevent players from zooming in while sprinting, but I think the utility of zooming in while crouching is reasonable and useful. I recommend having a separate state machine for zooming, something like camera_state. This would not only allow developers to implement multiple zoom modes (like mini zoom or super zoom), it would enable protecting camera tricks that may break when zoomed in.