[presets] add steamos files

presets/steam/steamos/steamos-polkit-helpers/steamos-reboot-other

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+set -eu
+
+if [[ $EUID -ne 0 ]];
+then
+    exec pkexec --disable-internal-agent "$0" "$@"
+fi
+
+exec /usr/bin/steamos-reboot --reboot-other
+