Touchpad gestures for X11 (XInput 2.4, X Server 21.1)
This MR implements touchpad gestures that have recently landed to X11 (https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/530, https://gitlab.freedesktop.org/xorg/proto/xorgproto/-/merge_requests/18) and will be released this year.
On a high level X11 touchpad gestures work in a similar way to Wayland. Both effectively route touchpad gesture events from libinput.
This MR has been tested to work on 3.24.20 with development versions of Xserver and related dependencies.
GDK_TOUCHPAD_GESTURE_MASK has been added to POINTER_EVENTS because that's how it's effectively done on gdk Wayland backend.