updated partial sums builder handle_named_function and handle_sum to …#619

natalieb-noaa wants to merge 2 commits intomainNOAA-GSL/VxIngest:mainfrom

613-update-partial-sums-handler-to-accept-param-object-that-contains-both-model-and-obs-var-namesNOAA-GSL/VxIngest:613-update-partial-sums-handler-to-accept-param-object-that-contains-both-model-and-obs-var-namesCopy head branch name to clipboard