New vocabulary API request: getRelatedConceptNames

[pbr6cornell]

We need a webAPI call that takes @conceptIdList and returns concept_name for all related concepts for a given @relatedVocabularyId and @relatedClassId

Use case: to be used in PENELOPE on the spontaneous report tab when we want to take a set of SNOMED concept ids and return back a list of MedDRA PT concept names. These concept names will then be sent to OpenFDA to summarize FAERS by outcome and seriousness.