Bug 32933: Use val() instead of attr("value") when getting field values with jQuery

Bug 32933: Use val() instead of attr("value") when getting field values with jQuery

This patch replaces instances in Koha's templates where "attr('value')" is
used to get the value of a form field, using "val()" instead. This
ensures that we get the current value of the field, not just the
value of the field when the page first loaded.

To test, apply the patch and test the following pages:

- Tools -> Tags. Use the "Check lists" form in the right-hand sidebar
  to test the approval status of some approved and rejected tags. It
  should correctly respond with the tag's status.
- Cataloging -> Label creator.
  - New -> Printer profile. Each offset and creep field should correctly
    reflect the selected value in the "Units" dropdown. Changing the
    dropdown should make the units change accordingly.
  - New -> Label template. Perform the same tests as above.
- Tools -> Patron card creator.
  - New -> Layout. If necessary, check the "Field 1" checkbox. The
    units should be displayed correctly and change as you change the
    "Units" dropdown.
  - New -> Printer profile,
  - New -> Card template: Perform the same tests as above.
- Lists -> List contents.
  - Check that the "Add to" dropdown menu works for adding selected
    titles to a cart or another list.
- Back record modification. Submit a batch of records for modification
  and go to Administration -> Manage jobs.
  - View the details of the job you just submitted.
  - Confirm that the "Add modified records to the following list"
    dropdown works correctly.
- Cataloging -> Find a bibliographic record -> Edit items.
  - Confirm that clicking a cell in the table of existing items
    triggers the "Edit item/Delete item" menu, and that these links
    work correctly.

Works as described.

Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>