[Test/HT] Added a new test using the staggered scheme

ProcessLib/HT/Tests.cmake

...atTransportInStationaryFlow_ts_50_t_50000.000000_mono.vtu

...ansportInStationaryFlow/HeatTransportInStationaryFlow.prj

...ow/HeatTransportInStationaryFlow_ts_50_t_50000.000000.vtu

...ggeredCoupling/HeatTransportInStationaryFlow/geometry.gml

...oupling/HeatTransportInStationaryFlow/geometry_bottom.vtu

...dCoupling/HeatTransportInStationaryFlow/geometry_left.vtu

...Coupling/HeatTransportInStationaryFlow/geometry_right.vtu

...edCoupling/HeatTransportInStationaryFlow/geometry_top.vtu

.../StaggeredCoupling/HeatTransportInStationaryFlow/mesh.vtu