Add two PhaseFields support in Restart/Migration/MigrationBECoProcessors

apps/cpu/LaminarTubeFlow/ltf.cfg

apps/cpu/LaminarTubeFlow/ltf.cpp

apps/cpu/Multiphase/Multiphase.cfg

apps/cpu/Multiphase/Multiphase.cpp

apps/cpu/ViskomatXL/viskomat.cfg

src/cpu/VirtualFluidsCore/CoProcessors/MPIIOCoProcessor.cpp

...alFluidsCore/CoProcessors/MPIIOMigrationBECoProcessor.cpp

...tualFluidsCore/CoProcessors/MPIIOMigrationCoProcessor.cpp

...irtualFluidsCore/CoProcessors/MPIIORestartCoProcessor.cpp

src/cpu/VirtualFluidsCore/Utilities/CheckpointConverter.cpp

src/cpu/VirtualFluidsCore/Utilities/CheckpointConverter.h