This commit adds a new feature to preselect the direction of the next
spawned window with a corresponding komorebic preselect-direction
command which takes an OperationDirection.
If the OperationDirection is valid from the current position, it will be
stored in the Workspace state, and then read, applied, and deleted when
the next manage-able window is spawned.
Direction preselection does not (yet?) support the Grid layout.
