New job to promote a build version as a release

Add a new simple pipeline running on the master branch with its related Jenkinsfile: promote.groovy.
This job is parametrized with a Nuxeo build version (such as 11.1.50) to promote a given build as a release.
For now it's triggered manually.

This job should:

• Checkout the build tag to promote.

  git checkout v11.1.50
  

• Update the new Maven POM, see NXP-28926, with the released version by removing -SNAPSHOT.

  11.1-SNAPSHOT -> 11.1
  

• Add a release commit.

  git commit -m "Release 11.1"
  

• Add a tag pointing to this release commit.

  git tag v11.1
  

• Update the master branch version to the next SNAPSHOT version. Also update the new Maven POM.

  11.1-SNAPSHOT -> 11.2-SNAPSHOT
  

• Validate the updated POMs and push to GitHub.
• Promote Maven artifacts form staging to prod, see NXP to be defined.
• Deploy the new Maven POM to packages.nuxeo.com, see NXP-29214
• Upload Nuxeo Packages to Connect prod, see NXP-28888.
• Promote the Docker images, see NXP-29096.