Add keyboard shortcuts for Elgato key lights

- create Gnome keyboard shortcuts to manage the Elgato key lights:
  + toggle
  + increase and decrease brightness
- we use Python scripts in ~/.config/gnome-settings/elgato
  based on the "leglight" PIP package
  (Source: https://gitlab.com/obviate.io/pyleglight)

.config/gnome-settings/elgato/toggle_keylights.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python
+
+import leglight
+
+LEFT_KEYLIGHT_IP = "192.168.20.72"
+RIGHT_KEYLIGHT_IP = "192.168.20.73"
+
+left = leglight.LegLight(LEFT_KEYLIGHT_IP, port=9123)
+right = leglight.LegLight(RIGHT_KEYLIGHT_IP, port=9123)
+
+if left.info()["on"] or right.info()["on"]:
+    left.off()
+    right.off()
+
+else:
+    left.on()
+    right.on()
+    left.brightness(30)
+    right.brightness(30)
+    left.color(6000)
+    right.color(6000)