Move the QMessageBox-displaying helper out of the logging utility into a
dedicated UI class. RiaLogging.h no longer pulls QMessageBox/QWidget into
the ~270 files that include it. Behavior is preserved: showError displays
the dialog when running interactively (and not under regression tests),
then forwards the text to RiaLogging::error.
Convert 11 file/directory path fields from QString to caf::FilePath across
ProjectDataModel classes for type safety and consistent path handling.
Fields converted: RimCalcScript::absoluteFileName,
RimScriptCollection::directory, RimBinaryExportSettings::fileName,
RimExportInputSettings::fileName, RimFractureExportSettings::fileName,
RimReservoirCellResultsStorage::m_resultCacheFileName,
RimProcess::m_workDir, RimWellIASettings::m_baseDir,
RimPlotTemplateFileItem::m_absoluteFileName,
RimWellMeasurement::m_filePath, RimFileWellPath::m_filePath.