JUBE integration for deliverable 3.6

In this issue branch, JUBE will be integrated to benchmark the WGAN model training on the Juelich HPC-systems Juwels Cluster and Juwels Booster as well as on the e4-cluster.
In addition to model training and inference, the newly developped data loader (continued work from #58 (closed), #55 (closed) and #52 (closed)) will be benchmarked as well.

A guideline incl. a blueprint for the JUBE integration is provided here.
The results of the benchmarking will be documented in this google spreadsheet.