Include fastcgi https parameter in generated nginx configuration

As a built-in documentation for trac issue #10273, update the web server stanza generated with `omero web config nginx` and `omero web config --system nginx` 
To test the PR: 
- retrieve Insight's Web Start descriptor from `https://<server_name>/webstart/jars/insight.jnlp`
- check that the `codebase` and `href` attributes correctly use the `https` scheme in the generated `jnlp` tag
- `javaws insight.jnlp` should load the application