Record build sources in Gitlab
requested to merge clemenci/LbNightlyTools:record-build-sources-in-gitlab into prepare-for-new-jenkins
if a project with the right name is available in https://gitlab.cern.ch/lhcb-nightlies, the commit used for the nightly build is pushed there as a tag (slot/id)
The projects in https://gitlab.cern.ch/lhcb-nightlies should be created as mirrors of the original projects.