Bug 2324: Adding confirm dialog when undoing import

Bug 2324: Adding confirm dialog when undoing import

EDIT: Comment 3

To test:
1) Go to Tools -> Staged MARC Management
2) Click on a batch to see details
3) If not already imported, then import, otherwise you should already see the button to undo import into catalog.
4) Click this button. Confirm you are asked to confirm. Confirm clicking Cancel will cancel the undo. Confirm clicking OK will continue with the undo.

Sponsored-by: Catalyst IT
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher <bredan@bywatersolutions.com>