feat: add proper openresty support

This change allows supporting the openresty package as installed on Ubuntu 18.04 from the official openresty package repository, while also returning general nginx support.

Closes #3675

docker/etc/runit/runsvdir/default/openresty/run

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+exec >>/var/log/services/openresty
+exec 2>&1
+
+echo "Running openresty"
+exec /usr/bin/openresty -c /usr/local/openresty/nginx/conf/nginx.conf -g "daemon off;"