Add support to configure node properties via environment variables

At the moment is not possible to configure server/node properties via environment variables. This is particularly useful when configuring secrets, e.g. basic authentication username and password.

It would be great to introduce some mechanism to support this. An example of how this could work is spring boot application properties, apache kafka docker images or even the AWS authentication chain.

For example, if the setting `server.auth.password` is configured via properties file, the value could be set/overwritten via env vars by setting `SERVER_AUTH_PASSWORD`. A good convention and resolution chain should be defined.

Start by reviewing how server and node properties are currently loaded from property files, then compare the environment-variable conventions suggested in the issue. Define the naming convention and precedence or resolution chain for values such as server.auth.password. Done means documented environment-variable support can configure and override node properties, including authentication credentials.

Written by the indexing model from the issue text.