Add postprocessing code for muon efficiencies 2D hists

Extended the HistGrinder yaml config files to process all 2D efficiency plots for MuonTracking offline DQM and added the Python function efficiencies_2d that does the calculation. The postprocessing will overwrite the corresponding 2d efficiency plots that are already present, but not yet correctly filled.

Furthermore, moved the non-cb efficiency plots to the expert directory, because they were determined to be unimportant for shiters. A couple of typos in the desription strings were also corrected.