Custom vertex container flag
This add a new functionality to IDPVM that lets the user specify the Primary Vertex collection, in case a dedicated collection is requested (i.e. Acts)
This is then used in a new ART test that will compare the ACTS and Default (i.e. Athena) primary vertex containers obtained by running full Acts or Athena workflows respectively, without EDM converters. The xml file only contains few variables, since link between acts track particles and acts tracks is still not in place. This test is basically checking that the ACTS standalone workflows manages to produce a reasonable primary vertex container, without relying on the legacy code.