Add updates to the xml description of the ATLAS feet, flexible chain and HFTruck

Hi,

for shifters/RC: please do not squash the commits since each commit is a separate update of the xml description of the passive materials and it would be good to keep the history.

This MR updates the xml description of the passive materials, i.e. the ATLAS feet, flexible chain and HFTruck in the AGDD xml format. This state of the file is used in the latest Run 2 muon layout MuonSpectrometer-R.08.02 (not used in production, but most recent status due to e.g. updates of the muon materials and clash fixes etc.).

Best, Nico