get_thumbnail_batch

[get_thumbnail_batch](https://www.dropbox.com/developers/documentation/http/documentation#files-get_thumbnail_batch) scope: `files.content.read` Get thumbnails for a list of images. We allow up to 25 thumbnails in a single batch. This method currently supports files with the following file extensions: jpg, jpeg, png, tiff, tif, gif and bmp. Photos that are larger than 20MB in size won't be converted to a thumbnail.