RimEclipseView_exportVisibleCells writes a FLUXNUM/MULTNUM/ACTNUM
keyword based on cell visibility in the view and requires an explicit
export file. The export keyword reuses
RicSaveEclipseInputVisibleCellsUi::ExportKeyword, registered as the
Python StrEnum VisibleCellsExportKeyword.
RicSaveEclipseInputVisibleCellsFeature::exportVisibleCells() is split
out of executeCommand() to return errors via std::expected instead of
only logging them.
RicfExportVisibleCells resolves the export folder from the command file
executor's CELLS export path and forwards to the object method. The
hand-written View.export_visible_cells() wrapper is removed since the
generated EclipseView method shadows it.
Kristian Bendiksen
Magne Sjaastad
Gaute Lindkvist