[enhancement]: Add flag to fail instead of warn when files aren't found.

[ChrisBras]

Task Name

FtpUpload@2

Describe your feature request here

I see the following warning in the pipeline log when files aren't found.
##[warning]Could not find any files to upload

I would like to have the ability to fail this instead of warn.

[aleksandrlevochkin]

Hi @ChrisBras thank you for the proposal, we are working on higher prioritized issues at the moment, but we'll get back to this one soon