tutorials/multiphase/reactingTwoPhaseEulerFoam/laminar/steamInjection: Improved stability

Main changes in the tutorial:
  - General cleanup of the phaseProperties of unnecessary entries
  - sensibleEnthalpy is used for both phases
  - setTimeStep functionObject is used to set a sharp reduction in time step near the start of the injection
  - Monitoring of pressure minimum and maximum

Patch contributed by Juho Peltola, VTT.