Provision a OKD4

Goal: Trigger an OKD4 cluster provision pipeline, wait for it to finish download the artefacts that it generates.

Tasks:

1. Trigger the OKD4 pipeline with the proper parameters;
2. Wait for the pipeline
3. Fetch the artefacts and store them

This issue is the first step to achieve the goal in https://gitlab.cern.ch/webservices/webframeworks-planning/issues/37

CC/ @efokas