Add ghost merging alg

This MR adds a new algorithm to JetAnalysisAlgorithms which combines multiple ghost track collections into one. This is useful to combine standard and LRT ghost tracks to be used by downstream algorithms.

Tagging @dguest who may be interested

PhysicsAnalysis/Algorithms/JetAnalysisAlgorithms/JetAnalysisAlgorithms/JetAnalysisAlgorithmsDict.h

@@ -10,6 +10,7 @@
 
 #include <JetAnalysisAlgorithms/JetCalibrationAlg.h>
 #include <JetAnalysisAlgorithms/JetGhostMuonAssociationAlg.h>
+#include <JetAnalysisAlgorithms/JetGhostMergingAlg.h>
 #include <JetAnalysisAlgorithms/JetModifierAlg.h>
 #include <JetAnalysisAlgorithms/JetSelectionAlg.h>
 #include <JetAnalysisAlgorithms/JetUncertaintiesAlg.h>