changes to make ALFA ROB Monitor MT safe

It is the first step in making ALFAROBMonitor MT safe. The main algorithm is now derived from AthReentrantAlgorithm and the execute method: StatusCode execute(const EventContext& ctx) const; Part of the variables were reorganized to avoid globals. New MonTool was added with new histogramming - the original histograms are also kept for reference (not MT safe) I run : runTrigART.py -m -j 4 and all 4 executed tests succeeded. The algo was also tested over ALFA calibration file collected in Run2