Create example showing how to get statistical uncertainties using the "history-by-history" method

Create example(s) showing how to get statistical uncertainties of additive quantities (e.g. dose) calculated with a scoring mesh using the "history-by-history" method
Source: User forum (see at https://geant4-forum.web.cern.ch/t/history-by-history-method-in-command-based-scoring/11571 )
See p. 7 of https://indico.cern.ch/event/1455551/contributions/6139454/attachments/2941430/5167948/UR_biomedical_guatelli_cortes_2024_final.pdf