Bug 32121: Show an alert when adding a checked out item to an item bundle

Bug 32121: Show an alert when adding a checked out item to an item bundle

When trying to add a checked out item to an item bundle, an alert
message will show up, giving the user a chance to return the item
immediately before adding it to the bundle

Test plan:
1. Create an item bundle (see bug 28854 comment 458)
2. Create a biblio with one item and check out this item.
3. Try to add the checked out item to the bundle
   You should see a message saying that the item is checked out. Next to
   this message should be a button "Check in and add to bundle".
4. Click on the button. There should be a message saying that the item
   was added to the bundle.
5. Close the modal window and verify that the item was correctly
   returned and added to the bundle

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>