Fix issue for reading hlt2 files
Fix issue related to the wrong unpacking of the hlt2 mc particles and vertices. To be merged together to LHCb!3352 (merged). A new qmtest is added for reading a hlt2 .dst and creating a tuple with FunTuple.
Work on DPA task https://gitlab.cern.ch/lhcb-dpa/project/-/issues/180. Somewhat related to https://gitlab.cern.ch/lhcb-dpa/project/-/issues/179.