Bug 16014: Display a warning on deleting OAI sets

Bug 16014: Display a warning on deleting OAI sets

A JavaScript alert should ask the user to confirm deletion of a OAI set.

Test plan:
Define a OAI set
Delete it
=> With this patch you should get a warning

Signed-off-by: Aleisha <aleishaamohia@hotmail.com>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>
(cherry picked from commit 5dc392f6638b7723a95007afadb23d2872c3f19f)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
(cherry picked from commit 7db11e9565fb94b0fe4c4c27b029c8dc71103f61)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>