Support "SW_ROTATE_LOCK" keys

Some devices have a physical "rotation lock" button (to lock screen rotation) and therefore the kernel may send such "SW_ROTATE_LOCK" event. This is for instance the case of the Wacom MobileStudio (and probably other tablet-like devices). See for instance this patch which is going to be available likely in Linux 4.16: https://bugzilla.kernel.org/show_bug.cgi?id=197991

Currently GNOME shell does not suppor these events and the button is just rendered useless.

Could this be supported? Thanks!