Clearly identify the build number of date of the Open ETP Server Docker image

When re-using or manipulating Docker images and tags of Open ETP Server it is difficult to know if it contains a given change or when it has been released, as tags can't be trusted.

As a devops deploying Open ETP Server using automated pipelines, I need to be able to identify easily the version/build number/build date of the Docker image I am deploying so that I can deduce if it contains a given change or not when I need to identify improvements or regression.

This could be easily done by adding one or more LABELs orARGs in the Docker image, of which the value can be dynamically set by the pipeline at build time.