Update generate_metap_agg.py script to source ids from new slot

[kheal]

This will depend on the completion of microbiomedata/nmdc-schema#2157 and microbiomedata/nmdc-schema#1253 and microbiomedata/issues#897.

We will need to heavily edit the generate_metap_agg.py script to source data from the newly refactored records to comply with the newly refactored FunctionalAnnotationAggMember class.

Once this is working and the data portal is updated to source only the functional_annotation_agg records, we can purge the original metap functional annotation records.

[kheal]

Going a different route, See #26