Bug 25280: Use modal confirmation when removing share from a list in the OPAC

Bug 25280: Use modal confirmation when removing share from a list in the OPAC

This patch updates the process of removing a share from a list in the
OPAC so that the confirmation request shown to the user is a Bootstrap
modal instead of a plain JavaScript confirm dialog.

To test you should have the OpacAllowSharingPrivateLists enabled.

 - Log in to the OPAC as a user who has multiple private lists.
 - Share two or more lists with another user in the system.
 - Accept the list shares on behalf of the other user and log in to the
   OPAC as that user.
   - In the list of that user's lists, test the process of removing a
     share:
     - Clicking "Remove share" should trigger a modal which asks if you
       want to remove sharing. It should show the name of the list in
       question.
     - Test the funcionality of both the "No" and "Yes" options.
     - Confirm that the "Remove share" button works correctly for any of
       multiple lists.
   - View the contents of a list which has been shared with this user.
     - Test the "Remove share" button at the top of the list's contents.
       - The same confirmation dialog should be triggered.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>