How to rotate NSStatusItem

Issue #720

NSStatusItem is backed by NSButton, we can animate this inner button. We need to specify position and anchorPoint for button’s layer so it rotates around its center point

guard
    let button = statusItem.button
else { return }

let animation = CABasicAnimation(keyPath: "transform.rotation.z")
animation.fromValue = 0
animation.toValue = CGFloat.pi * 2
animation.duration = 0.25
animation.repeatCount = 1
button.layer?.position = NSPoint(x: NSMidX(button.frame), y: NSMidY(button.frame))
button.layer?.anchorPoint = NSPoint(x: 0.5, y: 0.5)
button.layer?.add(animation, forKey: "rotate")