Bug 34566: Update MARC21 cataloging plugins with consistent footers

Bug 34566: Update MARC21 cataloging plugins with consistent footers

This patch updates MARC21 cataloging plugin templates so that submit and
cancel controls are consistently displayed in a fixed footer.

To test, apply the patch and go to Cataloging.

- Create or edit a bibliographic record
- Test the cataloging plugins for these fields:
  - 000 (Leader)
  - 006
  - 007
  - 008
  - In each case, confirm that the correct popup window is shown when
    you click the plugin link.
  - Confirm that clicking the "Cancel" button closes the window without
    copying any data to the field in the MARC editor.
    * Note that if the plugin is also triggered by cursor focus in the
      input field, some data may be automatically filled anyway.
  - Confirm that filing in data and clicking "Submit" will copy the
    correct information into the field.

- Go to Authorities and create or edit an authority record.
- Test the plugin for these fields:
  - 000 (Leader)
  - 008
 - Perform the same tests as above.

I don't think the marc21_field_008_classifications is used at all, but
the template has been updated anyway. To test, edit your authority
record to use the plugin:

 - Administration -> Authority types -> Default -> MARC structure -> 008
   -> Subfields -> Edit.
 - Under Advanced constraints -> Plugin, select
   "marc21_field_008_classifcations.pl"
 - Re-test the behavior of the authority editor's tag 008 plugin to
   confirm that this plugin is used and works correctly.

Signed-off-by: Émily-Rose Francoeur <emily-rose.francoeur@inLibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>