IDR List Metadata Keys

List the curated metadata attribute keys available for searching the Image Data Resource (IDR), for a given resource type. These are the valid 'key' arguments for IDR_search_images and IDR_search_studies, e.g. 'Gene Symbol', 'Gene Identifier', 'Organism', 'Cell Line', 'Compound Name', 'Antibody Name', 'Phenotype', 'Pathology', 'Sex', 'Age'. Use this first to discover what can be queried before building a search.