If shot button pressed too frequently image might loss on old iPhones

[Zwei-wei]

This is actually a feature request. Our UX stuff posted an issue about image lost on the old iPhone if press shot too quickly. So can we have something like func wrapperDidShotPress(_ imagePicker: ImagePickerController) and func wrapperDidShotFinish(_ imagePicker: ImagePickerController, image: UIImage) in delegate so we can do

func wrapperDidShotPress(_ imagePicker: ImagePickerController) {
        imagePicker.shotButton.isEnabled = false
}

func wrapperDidShotFinish(_ imagePicker: ImagePickerController, image: UIImage) {
        imagePicker.shotButton.isEnabled = true
}

[3lvis]

Thanks @Zwei-wei, happy to merge it if you make a PR!