new background histograms and AthenaMT monitoring tool

This is result of JIRA ticket ATR-19956. The changes cover using AthenaMT monitoring tool to build root structure with histograms being filled during a predefined number of LBs. The current version includes also the old-style booking and filling root histograms for comparison with the new ones. The code has been tested with raw data file: athenaHLT.py -c "enableALFAMon=True;" -c "setMenu='PhysicsP1_pp_run3_v1';" --imf --threads=1 --concurrent-events=1 --nprocs=1 -f=/afs/cern.ch/user/k/korcyl/ALFAROBMonitor/run/concatData._0001.data TriggerJobOpts/runHLT_standalone.py