xAODBtaggingEfficiency: add feature to BTaggingTruthTaggingTool to work in Continuous WP (Jira: AFT-382 )

Add new feature to the BTagginTruthTaggingTool to work in Continuous Working point to address this JIRA ticket: https://its.cern.ch/jira/browse/AFT-382

The code is preliminary:

• Add the property CutBenchmark to choose the cut value when running in Continuous WP

• Nominal has been tested in VHbb 1L and it works.

• Treatment of the systematics:

  • Add a feature to exclude some of the Eigenvectors from computation (i.e. the speed up computation)

  • Now the systematics are applied with m_effTool->applySystematicVariation(m_eff_syst[sys]) and not bin-by-bin, see L617. Is it enough?

Tagging @jshlomi, @lidiaz and @pberta