Pane dragging is limited on Wayland client

[D0ntPanic]

When using the Wayland client on Linux, panes cannot be dragged to new windows and cannot be dragged to a different, already existing window. In Wayland, panes can only be dragged within a single window.

The methods currently used to determine the target window are currently incompatible with Wayland. The methods used to display the drag indicator to show that a pane is being dragged also does not work on Wayland. Both of these are disabled in the current Wayland build.

These should be refactored to be Wayland compatible.