Bug 19429: Add confirm message when deleting invoice from invoice search page

Bug 19429: Add confirm message when deleting invoice from invoice search page

To test:
To test:
1) Go to Acquisitions
2) Go to Invoices (left nav menu)
3) Click Search (no need to filter results)
4) Click dropdown menu for an invoice, click Delete
5) Notice invoice is deleted instantly
6) Apply patch and repeat steps 3 and 4
7) Confirm the confirm message shows and works as expected

Sponsored-by: Catalyst IT
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>