[PCS] Add an option to separate the process variables by process

...ProjectFile/prj/processes/process/HT/t_coupling_scheme.md

...rj/processes/process/HYDRO_MECHANICS/t_coupling_scheme.md

...ses/process/HYDRO_MECHANICS_WITH_LIE/t_coupling_scheme.md

...le/prj/processes/process/PHASE_FIELD/t_coupling_scheme.md

...s/process/RichardsComponentTransport/t_coupling_scheme.md

...j/processes/process/THERMO_MECHANICS/t_coupling_scheme.md

ProcessLib/ComponentTransport/ComponentTransportProcess.cpp

ProcessLib/ComponentTransport/ComponentTransportProcess.h

...ib/ComponentTransport/CreateComponentTransportProcess.cpp

ProcessLib/HT/CreateHTProcess.cpp

ProcessLib/HT/HTProcess.cpp

ProcessLib/HT/HTProcess.h

ProcessLib/HydroMechanics/CreateHydroMechanicsProcess.cpp

ProcessLib/HydroMechanics/HydroMechanicsProcess-impl.h

ProcessLib/HydroMechanics/HydroMechanicsProcess.h

...essLib/LIE/HydroMechanics/CreateHydroMechanicsProcess.cpp

ProcessLib/LIE/HydroMechanics/HydroMechanicsProcess.cpp

ProcessLib/LIE/HydroMechanics/HydroMechanicsProcess.h

ProcessLib/PhaseField/CreatePhaseFieldProcess.cpp

ProcessLib/PhaseField/PhaseFieldProcess-impl.h