Closing all editors: move dirty editor to the front when asking to confirm

[bpasero]

Steps to Reproduce:

1. open multiple editors across multiple groups
2. make some of them dirty across multiple groups
3. click "Close All" action from "Open Editors" view

=> it would be good if the first dirty editor in each group is being revealed so that the user can review the changes before making a choice. We do the same when closing all editors in a single group.

=> today we just ask in a single dialog for all files (which is intentional) but we do not show the dirty files in each group