Optionally include more fields with the DSD #1
Description
In imf_get_datastructure, we currently omit the 'conceptIdentity' and 'conceptRoles' fields (which allow mapping to concept metadata that describe the field). These are list fields, so to populate them, we would need to either expand the dataframe to tidy format, or use paste(x$conceptRoles, collapse = ",") to create a comma-separated character field.
We should consider adding an option to include this, or perhaps exposing some other function to get the related concept that describes the dimension.
We are also omitting the 'annotations' field. In all cases I've looked at, this field is empty. However, we should explore whether there are any cases where it isn't empty (in which case we may want to support optionally returning it).
body$data$dataStructures[[1]]$dataStructureComponents$attributeList also looks interesting as a source of metadata for data interpretability.