x11_common: handle window dragging in ButtonPress event

[na-na-hi]

Begin the _NET_WM_MOVERESIZE window dragging in ButtonPress event to match the behavior of win32 and wayland, simplify logic by dropping the win_drag_button1_down hack required by the old method, and fix a race condition described in commit 19f101db680f966a6e56035a16784541be390982, which happens when moving the mouse and releasing the button at the same time.

The race condition can be easily triggered when using a touch screen (tested with libinput driver), where a tap is translated to MotionNotify, ButtonPress, MotionNotify, and ButtonRelease in sequence, with the last 2 events having the same timestamp. This has caused some window managers to not stop dragging after the ButtonRelease, resulting in window being stuck in dragging state after a single tap.