get https://{server}/api/v2.1/dtable/app-download-link/
Get the file download link of a base's attachment.
The download link is only valid for a short time
The download link is only valid for some hours. After that the download link must be created again. We recommend
to store images on public hosting services like AWS S3 and saving only the links in SeaTable, allowing direct use of image links in web pages.