[algo] Prepare DigiEventQa for Histo publication

- Add to DigiEventQaConfig a static method to get the name of digi time histos (avoid copies w/ risk of divergence)
- Add in DigiEventQaConfig a method to get Config strings for all histos (ensure same output folder)
- Add in DigiEventQaConfig a method to get Config strings for all canvases + prepare it for Digi Time in Event canvas
- Change storage for Histo1D in DigiEventQaData to a vector + modify map to provide reference to entry in it (preparation for addition of other histograms)
- Add GetConfig accessor to DigiEventQa