This commit adds a new SocketMessage variant PromoteSwap and
corresponding komorebic promote-swap command.
PromoteSwap will also promote the focused window container to the
largest tile in the layout, but instead of removing the focused
container x from the Ring and inserting it into position 0, possibly
changing the positions of other windows between 0 and x, the indices x
and 0 in the Ring will be swapped directly.