Add initial files for building superset

This commit comprises the first steps in building an image for Superset. It does not yet publish the image, nor does it include the customisations required for our specific instances.

It is an interpretation of the upstream Dockerfile to be found here: https://github.com/apache/superset/blob/master/Dockerfile

At the moment the latest release of version 3.0.2 has been selected.

Bug: T352165