Draft: Expand the Magnetic field test so as to cover recent FPE issues

Ping

@schaffer and @jmaurer . This shows the "0,0,0" that causes the FPEs when Toroid off.

Note since we statically link to Geant4 one needs to have these

+ MagneticField/MagFieldUtils                                                      
+ Simulation/AtlasGeant4                                                           
+ MagneticField/MagFieldServices                                                   
+ Simulation/ISF/ISF_FastCaloSim/ISF_FastCaloSimParametrization   

ping @jchapman

The issue is

MagFieldCondReader                                     1     0    INFO Field xyz: -161.341, 1063.34, 2171.6, -5.7681e-05, 0.000373872, 0.00168503

if all on

then

MagFieldCondReader                                     8     0    INFO Field xyz: -161.341, 1063.34, 2171.6, -0, 0, 0

when toroid off .

This is what I am failing to parse 100%.

Feel free to ping other Magnetic Field experts. Not sure if the code is buggy or the map or a combination, or really should be 0 there?