feat(darwin): add sketchybar to yabai module

modules/nix-darwin/yabai/sketchybar/plugins/battery.sh

@@ -0,0 +1,34 @@
+#!/bin/sh
+
+PERCENTAGE=$(pmset -g batt | grep -Eo "\d+%" | cut -d% -f1)
+CHARGING=$(pmset -g batt | grep 'AC Power')
+
+if [ ${PERCENTAGE} = "" ]; then
+  exit 0
+fi
+
+case ${PERCENTAGE} in
+  9[0-9]|100)
+      ICON="􀛨"
+      ;;
+  [6-8][0-9])
+      ICON="􀺸"
+      ;;
+  [3-5][0-9])
+      ICON="􀛩"
+      ;;
+  [1-2][0-9])
+      ICON="􀛩"
+      ;;
+  *)
+      ICON="􀛪"
+      ;;
+esac
+
+if [ ${CHARGING} != "" ]; then
+  ICON="􀢋"
+fi
+
+# The item invoking this script (name ${NAME}) will get its icon and label
+# updated with the current battery status
+sketchybar --set ${NAME} icon="${ICON}" label="${PERCENTAGE}%"