Main hgtd cluster test
Add new HGTDCluster class using the xAOD EDM format.
New class and accompanying container and auxiliary container added under Event/xAOD/xAODInDetMeasurement.
MR connected to QP ATLIDTRKCP-502 : https://its.cern.ch/jira/browse/ATLIDTRKCP-502
Edited by Dimitris Ntounis