When the operations popover is not visible, we have to give
feedback to the user about if an operation finished.
For that, show a in-app notification in case the operation popover
is closed and a operation finishes. Also, to link the notification
with the operation button, make the button pulse for a second.

The code interaction between nautilus-file-operations and nautilus-progress-info
start to get crowed. At some point, the best we can do is delegate all the
progress UI part to nautilus-progress-info, providing all the needed information
like the CommonJob, TransferInfo and SourceInfo; so we avoid the current
odd interaction between them. This is a future work.