Orchestrator to monitor and coordinate nightly builds

When releasing having different build ids for images/internal images/lxc and so on make me waste time collecting stuff from different places, as they often annoyingly differ by a minute or so.

It is also problematic on the LAVA reports app for the same reason.

To address that, this repository contains an orchestrator pipeline that computes a build id and then triggers a few child pipelines that use it.

The idea is to set a centralized schedule on this pipeline to replace the schedules set on each project.

In the future this pipeline may be also a good place to stick a manual job to turn a build into a release or release candidate, automating a step which now involves manually ssh'ing to aura and calling a script.