IN: mongo - active connection to the MongoDB instance. gridfsBucketName - full path to the GridFS parent of collections .files and .chunks. id - the file object ID, i.e., it's "_id" value. RETURN: The entire file contents in an array.
IN: mongo - active connection to the MongoDB instance. gridfsBucketName - full path to the GridFS parent of collections .files and .chunks. name - file name RETURN: The entire file contents in an array.