Bug 29713: Make item table when placing an item level hold sortable

Bug 29713: Make item table when placing an item level hold sortable

This patch modifies the holds page in the OPAC so that users selecting a
specific item to place a hold on can sort the table of items.

This patch also removes some obsolete JavaScript left over from before
Flatpickr.

To test, apply the patch and go to Administration -> Circulation and
fine rules to make sure at least one item type in your system has
"OPAC item level holds" set to "allow."

- Log in to the OPAC as a user who can place holds.
- Search the catalog for items which will accept item-level holds.
- Place a hold on one of the results, and click the "Show more options"
  link on the holds page.
  - Check the "specific item" radio button.
  - A table of items should be displayed. Confirm that the table is
    sortable.
  - The first entry in the table should be selected.
  - Perform the same test when placing a hold on multiple titles.
    Confirm that each table of items is sortable.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>