Check upload file size

It would be useful for smaller instances like RPi, if size of a file is checked before upload starts.

On RPi4 with Rasperian there is still the 32bit limit. Files up to 3,9GB can be uploaded, but upload also starts for larger files. While a 3,9GB file is stored successfully, a larger file just cause an error after upload. This error message is not understandable for an average non techy user.

If would be helpful to have a filesize check and print a message like “This file is to large for upload”, if the file is to large.

At least it would be nice to have a fixed message on all shared folders to tell the user the upload limit. (I know I can display custom messages on a share, but to do this on every share manually is a pain and should be done globally instead).