window: Remove unused condition

IS_WAYLAND_RESIZE will always result in a RESIZED result, at least.
window: Move move_resize_wayland to window-wayland.c

The move/resize logic is still busted for top/left resizes... sigh.
window-wayland: Fix resizing from the top/left once more

Restoring the position in our move_resize_internal implementation
is too late. We need to do it at ack-time, before we hand off the
new position to the constraints code.