Update exporter for new THERMAL_BC namelist
The DS_BOUNDARY_CONDITION and DS_INTERFACE_CONDITION namelists were replaced by a single common THERMAL_BC namelist. This also modifies labels and defaults in the UI for thermal boundary conditions.
The DS_BOUNDARY_CONDITION and DS_INTERFACE_CONDITION namelists were replaced by a single common THERMAL_BC namelist. This also modifies labels and defaults in the UI for thermal boundary conditions.