Create a private staging repository

Public packages have a staging repository used to store date-based releases: https://mavenin.nuxeo.com/nexus/content/repositories/nightly-staging/
Something similar is needed if we need to create a date-based release of any private package.

• create https://mavenpriv.nuxeo.com/nexus/content/repositories/nightly-staging-priv/ (make sure config is similar to https://mavenin.nuxeo.com/nexus/content/repositories/nightly-staging/)