[feature-request] Allow `/upload` of remote files (via intermediate temporary download)

[jmetz]

Idea is pretty straight forward as explained in title:

For /upload arguments starting with http:///https://,

• get file to temp location
• then upload file as usual

NB: could potentially pave the way for additional plugins etc, eg uploading via a tenor search, or some other web resource that can end up resulting in a downloaded file.