Comment 5 for bug 1913604

Pull request here: user/sandbergja/lp1913604_course_associate_items_at_other_libraries

Link here: https://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/sandbergja/lp1913604_course_associate_items_at_other_libraries

Testing notes from the commit message:

1) Create a new course at a branch that can have items (BR3, for example).
2) Add an item with the circ_lib of BR3. Note that the item is added to the grid.
3) Add an item with a different circ_lib. Note that you get an alert showing that the item is not at the course's owning library.
4) Push the Cancel button. Notice that the item is not added to the course.
5) Repeat step 3 and push the Confirm button. Notice that the item is added to the course this time.