Setup ci

Created a Cx pipeline for the KIT part of the project. It consists of several types of pipelines:

• Basic tests validating the configuration
• End-to-end tests for the full workflow for the 3 ART templates on two HPC systems (HoreKa and Levante)
• Ent-to-end tests for each individual job for the NWP_EXT_DATA template on Levante

Closes #45 (closed).