[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

algo/qa/DigiEventQa.cxx

 /* Copyright (C) 2023 GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt
    SPDX-License-Identifier: GPL-3.0-only
-   Authors: Volker Friese [committer] */
+   Authors: Volker Friese [committer], P.-A. Loizeau */
 
 #include "DigiEventQa.h"
 
@@ -20,18 +20,21 @@ namespace cbm::algo::evbuild
 
     // --- Instantiate return object
     DigiEventQaData result;
+    result.fVectHistos.reserve(fConfig.fData.size());
     for (const auto& entry : fConfig.fData) {
       ECbmModuleId subsystem = entry.first;
-      string hist_name       = "digi_time_" + ::ToString(subsystem);
       auto& detConfig        = fConfig.fData.at(subsystem);
-      result.fDigiTimeHistos.try_emplace(subsystem, detConfig.fNumBins, detConfig.fMinValue, detConfig.fMaxValue,
-                                         hist_name);
+      result.fVectHistos.emplace_back(detConfig.fNumBins, detConfig.fMinValue, detConfig.fMaxValue,
+                                      DigiEventQaConfig::GetDigiTimeHistoName(subsystem));
+      result.fDigiTimeHistos.emplace(subsystem, result.fVectHistos.back());
     }
 
     // --- Event loop. Fill histograms.
-    for (const auto& event : events)
-      for (auto& subsystem : fConfig.fData)
-        QaDigiTimeInEvent(event, subsystem.first, result.fDigiTimeHistos.at(subsystem.first));
+    for (const auto& event : events) {                  //
+      for (auto& subsystem : result.fDigiTimeHistos) {  //
+        QaDigiTimeInEvent(event, subsystem.first, subsystem.second);
+      }
+    }
     result.fNumEvents = events.size();
 
     return result;

algo/qa/DigiEventQa.h

 /* Copyright (C) 2023 GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt
    SPDX-License-Identifier: GPL-3.0-only
-   Authors: Volker Friese [committer] */
+   Authors: Volker Friese [committer], P.-A. Loizeau */
 
 #ifndef ALGO_QA_DIGIEVENTQA_H
 #define ALGO_QA_DIGIEVENTQA_H 1
@@ -25,8 +25,10 @@ namespace cbm::algo::evbuild
    ** @since 16 June 2023
    **/
   struct DigiEventQaData {
-    std::map<ECbmModuleId, Histo1D> fDigiTimeHistos = {};
-    size_t fNumEvents                               = 0;
+
+    std::vector<Histo1D> fVectHistos                 = {};
+    std::map<ECbmModuleId, Histo1D&> fDigiTimeHistos = {};
+    size_t fNumEvents                                = 0;
   };
 
 
@@ -72,6 +74,37 @@ namespace cbm::algo::evbuild
         fData[detector] = {numBins, tmin, tmax};
       }
     }
+    static std::string GetDigiTimeHistoName(const ECbmModuleId& subsystem)
+    {
+      return "digi_time_" + ::ToString(subsystem);
+    }
+    std::vector<std::pair<std::string, std::string>> GetHistosConfigs() const
+    {
+      std::vector<std::pair<std::string, std::string>> cfg {};
+      for (const auto& entry : fData) {
+        cfg.push_back(std::pair<std::string, std::string>(GetDigiTimeHistoName(entry.first), "DigiEvtQa"));
+      }
+      return cfg;
+    }
+    std::vector<std::pair<std::string, std::string>> GetCanvasConfigs() const
+    {
+      /// => Format is "CanvasName;Canvas Title;NbPadX(U);NbPadY(U);ConfigPad1(s);....;ConfigPadXY(s)"
+      /// => Format of Pad config is
+      ///    "GrixX(b),GridY(b),LogX(b),LogY(b),LogZ(b),(HistoName1,DrawOptions1),...,(HistoNameZ,DrawOptionsZ)"
+      /// => See core/base/utils/fles/CbmFlesCanvasTools for the full code, especially GenerateCanvasConfigString
+
+      // --- Canvas of all Time in event per system
+      std::pair<std::string, std::string> cfgDigiTimeAll {"digiEvtTimeQaCanv", "digiEvtTimeQaCanv;"};
+      cfgDigiTimeAll.second += "Digi time in Events per subsystem;";
+      cfgDigiTimeAll.second += std::to_string(fData.size() / 2 + fData.size() % 2) + ";2;";
+      for (const auto& entry : fData) {
+        cfgDigiTimeAll.second += std::string("1,1,0,1,0,(") + GetDigiTimeHistoName(entry.first) + ",hist);";
+      }
+      if (fData.size() % 2) {  // Empty pad if odd number of systems
+        cfgDigiTimeAll.second += std::string("1,1,0,1,0,;");
+      }
+      return std::vector<std::pair<std::string, std::string>> {cfgDigiTimeAll};
+    }
   };
 
 
@@ -97,6 +130,9 @@ namespace cbm::algo::evbuild
     /** @brief Info to string **/
     std::string ToString() const;
 
+    /** @brief Const access to Qa config **/
+    const DigiEventQaConfig& GetConfig() const { return fConfig; }
+
 
   private:  // methods
     /** @brief Fill histogram with digi time within event