Add more file operation notification actions and time estimate

[zhanghai]

• Add pause, resume?
• Use content text for progress and sub text for estimation.

[christianfl]

Thank you really much for this beautiful app.

Just wanted to add that this would be a really useful feature especially with SMB/network share. Copying a few GB (over the internet) can drastically slow down copying so that an estimate would make really sense in order to decide wether or not to cancel that operation.