GeoPcon and GeoPgon: extended the interface to allow const access to memory buffers of the member vectors

This change was implemented to simplify Geo2G4 translation. In particular, it should allow passing the buffers held by GeoPcon and GeoPgon to the constructors of G4Polycone and G4Polyhedra respectively (see the discussion on Athena MR!74223 )

GeoModelCore/GeoModelKernel/GeoModelKernel/GeoPcon.h

@@ -70,16 +70,31 @@ class GeoPcon : public GeoShape {
       return m_zPlane[i];
   }
 
+  // Get a pointer to the memory buffer with Z Positions
+  const double* getZPlaneBuff() const {
+    return m_zPlane.data();
+  }
+
   //    Get the RMin of the specified plane.
   double getRMinPlane(unsigned int i) const {
       return m_rMinPlane[i];
   }
 
+  // Get a pointer to the memory buffer with RMin-s
+  const double* getRMinBuff() const {
+    return m_rMinPlane.data();
+  }
+
   //    Get the Z Position of the specified plane.
   double getRMaxPlane(unsigned int i) const {
       return m_rMaxPlane[i];
   }
 
+  // Get a pointer to the memory buffer with RMax-s
+  const double* getRMaxBuff() const {
+    return m_rMaxPlane.data();
+  }
+
   //    Executes a GeoShapeAction
   virtual void exec (GeoShapeAction *action) const;