Add schemas related tasks to jenkinsfile
Add schemas related tasks to jenkinsfile

This adds the ability to trigger builds of dependent apps in publishing api CI, and also uses a temporary (while we transition schemas to this repo) parameter, 'USE_PUBLISHING_API_FOR_SCHEMAS' which will allow the builds to report back their status to the publishing api branch and commit that triggered them, while ensuring that their success does not trigger a deployment.

alphagov/publishing-api,alphagov/publishing-api