Deleting an unsaved file displays "external change" notification

[JeffryBooher]

Open a file and make some changes to it
don't save
right click on the file in the file tree > delete
==> "External Change"

This is coming from the FileSyncManager.presentConflicts

This is fine when the change is external but we should try to avoid this dialog and prompt the user to save before deleting the file on disk. It's a confusing user experience.

[JeffryBooher]

Note: this was tested with 0.43 but does #9400 prevents the display of any warning in 0.44

[peterflynn]

@JeffryBooher I believe this is a dupe of #8610 and/or #4760. #8610 does already discuss showing a prompt before the deletion instead of waiting until after.

[JeffryBooher]

closing as dup