waybar: Add keepawake module

Shows if the pc will not automatically turn off screen or suspend.
Figures this out by checking for `swayidle` process, so that is
required. Turns on suspend again on click, and uses voidlinux `sv` user
service for it, so those have to be set up.

desktop/.config/waybar/modules/keepawake

@@ -0,0 +1,9 @@
+#!/usr/bin/env sh
+
+status="idle-disabled"
+if pgrep -x swayidle >/dev/null; then
+    status="idle-enabled"
+fi
+
+printf "{\"text\": \"\", \"alt\": \"%s\", \"tooltip\": \"\", \"class\": \"\"}" \
+    "$status"