Make visualFocus customizeable

visualFocus is a somewhat misleading name. There's no reason to assume that keyboard related FocusReasons are always more visual than MouseFocusReason or other types, but I understand the intent was to allow cleaner visuals for mouse users and more accessible focus visuals for keyboard users. I think it would be better if this property was customizeable, but with default behavior that matches the current behavior. That way visualFocus means whatever conditions the developers/designers think should get extra focus visuals rather than just being an odd name for something that is really just activeFocus && keyboard related FocusReasons.