IN: mongo - active connection to the MongoDB instance.
gridfsBucketName - full path to the GridFS parent of collections .files and .chunks.
ids - array of file object IDs, i.e., their "_id" values.
RETURN: An associative array containing id -> entire file content mappings.
IN: mongo - active connection to the MongoDB instance. gridfsBucketName - full path to the GridFS parent of collections .files and .chunks. ids - array of file object IDs, i.e., their "_id" values. RETURN: An associative array containing id -> entire file content mappings.