From time to time, it may be necessary to build or rebuild versions of the newinstall base container that are not the default in the Jenkins build matrix configuration. This can occur when a new build (e.g. with a necessary pin) is back-ported to an old rubin-env version or when a new not-latest rubin-env version is built for a release.

Allow the build-newinstall job to take a parameter specifying the version of the container to build.