[FEAT] OpenShift support / Run nginx unprivileged

[Fearvel]

Description
I would like to run elasticvue in a OpenShift cluster.
OpenShift requires that a pod is unprivileged which the chosen nginx base image does not support.

The easiest way to support OpenShift and other platforms that require a unprivileged user inside the container would be to switch to the official unprivileged image of nginx, See link below.
https://hub.docker.com/r/nginxinc/nginx-unprivileged

You can find a patch below which changes the Dockerfile from nginx to nginxinc/nginx-unprivileged
OpenShift-support.patch