Support keybindings for using 4k monitor

I'm not sure I'm sold on the "D{0,1}" keybindings. The thought was that 0 would
indicate off and 1 would indicate on. This seems sensible to me. I'm hesitant
because I don't think I have precedent for this idiom in any of my existing
keybindings.

I'm also not sure I like these being leader-prefixed keybindings.

configs/shared/.emacs.d/wpc/display.el

@@ -23,6 +23,9 @@
 ;; Constants
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+(defconst display/install-kbds? t
+  "When t, install the keybindings defined in this module.")
+
 ;; TODO: Consider if this logic should be conditioned by `device/work-laptop?'.
 (defconst display/laptop-monitor "eDP1"
   "The xrandr identifier for my primary screen (on work laptop).")
@@ -53,5 +56,12 @@
    :command (string/format "xrandr --output %s --off"
                            display/4k-monitor)))
 
+(when display/install-kbds?
+  (general-define-key
+   :prefix "<SPC>"
+   :states '(normal)
+   "D0" #'display/disable-4k
+   "D1" #'display/enable-4k))
+
 (provide 'display)
 ;;; display.el ends here