DaVinciTutorials tests - add ntuple content checks

Hello @amathad, @pkoppenb, first stab at this work we talked about, first for the DaVinciTutorials package.

Most ntuple content checks here are trivial, but this kind of check should hopefully prevent in the future issues such as those reported at #97 (closed) and #100 (closed). We now have examples on which to take inspiration for checks of any ntuple produced in any DaVinci test.