Draft: [trigEGam] Integration beteween mongroups and TrigEgammaMonitoring

This MR is to include mongroups inside the TrigEgammaMonitoring framework.

• A method was implemented in the TrigEgammaMonitCategoryMT reading, for now, the mongoups from JSON local file produced by a ART test.
• At this moment, only the primary chains was configured, and then, called inside the TrigEgammaMonitorConfigMT.py file .
• In a next MR, we will include a logic to route chains to shifter and expert folders automatically, according to their respective mongroups.

JIRA Ticket: ATR-25841 .

ping: @safarzad , @cjmeyer , @fernando , @kyjones and @jlieberm

Calorimeter/CaloTriggerTool/CaloTriggerTool/LArTTCellMap.h

 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef CALOTRIGGERTOOL_LARTTCELLMAP_H
@@ -54,7 +54,10 @@ public:
   Identifier whichTTID(const Identifier & id) const; 
 
   /** return the persistified map */
-  LArTTCell_P* getP() ; 
+  const LArTTCell_P* getP() const ;
+
+  /** return the persistified map (non-const) */
+  LArTTCell_P* getP() ;
  
   /**  initialize from POOL */
   void set(  const LArTTCell_P& t ) ;