Bug 25281: Use modal confirmation when deleting a list in the OPAC

Bug 25281: Use modal confirmation when deleting a list in the OPAC

This patch modifies the process of deleting a list in the OPAC so that
the deletion confirmation alert is replaced with a Bootstrap modal.

In the process, I moved the repeated deletion form markup into a block

To test, apply the patch and log in to the OPAC as a user who has
multiple lists, including some which have been shared with other users.

Go to the list of your lists and click the "Delete" link next to any of
your lists. It should trigger a confirmation modal:

 - The modal should show the title of the list you're deleting.
 - If the list has titles on it, it show how many.
 - If the list has been shared with someone it should say so.

Next, view a list which is not empty.

 - Test the "Delete list" link in the toolbar.
 - You should see the same information in the confirmation message as in
   the previous step.

Do the same with a list which is empty.

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>