This object uses standard evalutation to subset a mudata object using
character vectors of datasets, params, and locations. The result is subsetted such
that all rows in the data table are documented in the other tables (provided)
they were to begin with. It is preferred to use select_locations,
select_params, and select_datasets to subset a mudata object,
or filter_data, filter_locations, filter_params,
and filter_datasets to subset by row while maintaining internal
consistency.