Rim3dView_exportContourMapToText exports the contour map of an Eclipse
or GeoMech contour map view. The implementation is extracted from the
RICF_SOURCE_INIT feature RicExportContourMapToTextFeature into a static
helper returning std::expected, used by both the object method and the
legacy command.
The Python EclipseContourMap/GeoMechContourMap.export_to_text() wrappers
are kept as aliases of the generated method.