node upload & download with gridfs reference

reference:
https://www.youtube.com/watch?v=3f5Q9wDePzY
https://grokonez.com/node-js/gridfs/nodejs-upload-download-files-to-mongodb-by-stream-based-gridfs-api-mongoose
https://stackoverflow.com/questions/47667231/nodejs-streaming-multiple-files-from-readstream-gridfs-to-show-on-frontend
https://github.com/aheckmann/gridfs-stream

https://github.com/aheckmann/gridfs-stream/issues/125