Snap deployment for Duplicati

I think it would be nice to have a Snap deployment for Duplicati. There is already a Docker version. But docker messes up with RPi I/O. That’s when I thought that a Snap based version might be good. This will also help the application to auto-update to a newer version if needed.

Publish snap(craft) image for Duplicati #2689 is the GitHub issue version of this enhancement request.