detectorGeometries

This MR adds

• root files containing the sensitive hits of the different dd4hep detector geometries in acts-framework/Detectors/DD4hep/compact (https://gitlab.cern.ch/acts/acts-framework/tree/master/Detectors/DD4hepDetector/compact)
• some screen shots in order to have a quick look at the detectors without the need to open the root files In future the root files could be used for integration tests, to ensure, that geometry building is not broken.

Detectors/DD4hepDetectors/CLIC/README.md

+Command to re-create the root file:
+
+./build/bin/ACTFWDD4hepExtrapolationExample --dd4hep-input="file:Detectors/DD4hepDetector/compact/CLIC/Simple_CLIC.xml"
+
+Caution: Only sensitive hits have been printed out. In order to reproduce the root file, one needs to set all other prin-outs to `false`.