Add sunshine as an optional background service

overlay/etc/supervisor.d/sunshine.ini

@@ -0,0 +1,20 @@
+
+[program:sunshine]
+priority=50
+autostart=false
+autorestart=true
+# Retry a restart a few times.
+#   The start-sunshine.sh script has a section that will wait for the
+#   X server to become available before executing sunshine. However, this will time out after 30 seconds.
+startretries=10
+user=%(ENV_USER)s
+directory=/home/%(ENV_USER)s
+command=/usr/bin/start-sunshine.sh
+environment=HOME="/home/%(ENV_USER)s",USER="%(ENV_USER)s",DISPLAY="%(ENV_DISPLAY)s",XDG_RUNTIME_DIR="%(ENV_XDG_RUNTIME_DIR)s"
+stopsignal=INT
+stdout_logfile=/home/%(ENV_USER)s/.cache/log/sunshine.log
+stdout_logfile_maxbytes=10MB
+stdout_logfile_backups=7
+stderr_logfile=/home/%(ENV_USER)s/.cache/log/sunshine.err.log
+stderr_logfile_maxbytes=10MB
+stderr_logfile_backups=7