Improve Nuxeo build pipeline

When doing a build of Nuxeo, we may end up with having a Docker image available on packages.nuxeo.com but no Nuxeo packages on Connect preprod.
We need to reorganize the pipeline steps:

• build, package, tests - until the Docker image tests
• Git tag
• Deploy Maven artifacts internally
• Upload Nuxeo packages to Connect preprod - make the build fails if there is any issue
• Upload the Docker images to packages.nuxeo.com

When the pipeline succeed, update the job description with the build version: "Build 11.1.14" for instance.

Introduce an environment variable DRY_RUN that will allow the pipeline to skip some stages, such as the git tag and push, the packages upload, ...
This var could be set to true on the JX Platform Staging environment for instance.