HGCal Material Budget Validation

* Add a new SimWatcher plugin for HGCal and a configuration to run the validation

After merging this branch, simply run:
```
cmsRun Validation/Geometry/python/single_neutrino_cfg.py
cmsRun Validation/Geometry/test/runP_HGCAL_cfg.py
```
The histograms are produced in matbdg_HGCAL.root file