Add e_from_p_T() unit test for IdealGasFluidProperties.
Add e_from_p_T() unit test for IdealGasFluidProperties.

Refs #11133.

lindsayad/moose,andrsd/moose,bwspenc/moose,bwspenc/moose,jessecarterMOOSE/moose,permcody/moose,dschwen/moose,jessecarterMOOSE/moose,jessecarterMOOSE/moose,nuclear-wizard/moose,SudiptaBiswas/moose,andrsd/moose,idaholab/moose,permcody/moose,harterj/moose,SudiptaBiswas/moose,SudiptaBiswas/moose,milljm/moose,sapitts/moose,jessecarterMOOSE/moose,milljm/moose,YaqiWang/moose,lindsayad/moose,YaqiWang/moose,permcody/moose,laagesen/moose,harterj/moose,laagesen/moose,harterj/moose,sapitts/moose,laagesen/moose,permcody/moose,lindsayad/moose,jessecarterMOOSE/moose,laagesen/moose,bwspenc/moose,dschwen/moose,idaholab/moose,andrsd/moose,dschwen/moose,milljm/moose,lindsayad/moose,bwspenc/moose,nuclear-wizard/moose,nuclear-wizard/moose,dschwen/moose,laagesen/moose,YaqiWang/moose,bwspenc/moose,harterj/moose,milljm/moose,SudiptaBiswas/moose,andrsd/moose,idaholab/moose,sapitts/moose,sapitts/moose,lindsayad/moose,idaholab/moose,milljm/moose,idaholab/moose,harterj/moose,sapitts/moose,andrsd/moose,dschwen/moose,nuclear-wizard/moose,YaqiWang/moose,SudiptaBiswas/moose