Flavour-tagging implementation at trigger-level (AFT-485)

AFT-485: Implementation of the offline flavour-tagging code at trigger-level. Code can be tested by executing the file Trigger/TrigValidation/TrigUpgradeTest/test/test_trigUpgr_py_full_menu_build.py (add "doEmptyMenu=True;doBjetSlice=True;" to ex.args in order to run only the Bjet slices; Increase the number of events, otherwise Btag code might not be called, e.g. ex.max_events = 10000) Unsure if all slices are executed Offline flavour-tagging code uses defaults set by BTaggingFlags.py. At the moment changed defaults in BTaggingFlags.py to match trigger needs. Could edit the BTagging config files with 'if scheme == "Trig": ...'