Add keybinds to `consume` windows to the _left_ (default behaviour is to consume/expel from/to the right).

[jtaala]

Is your feature request related to a problem? Please describe. Add keybinds to consume windows to the left (default behaviour is to consume/expel from/to the right).

Additional context This is related to #679 which adds options on where to create new windows (i.e. to the left of the current window etc.).

This would implement analogous behaviour for consuming/expelling windows.