Bug 25321: Move translatable strings out of strings.inc into the corresponding JavaScript

Bug 25321: Move translatable strings out of strings.inc into the corresponding JavaScript

This patch moves string definitions out of strings.inc and into the
corresponding JavaScript files.

To test, apply the patch and test various pages in the staff interface:

A few suggestions:

- Perform a catalog search and view the detail page for a bibliographic record.
  - Confirm that the search results browser in the left-hand sidebar
    work correctly and that the title attributes of the controls are
    correct.
- Locate a patron with multiple checkouts. View the checkout page and
  test the various controls in the table of checkouts: Renew, check in,
  return claims, etc.
- View the list of holds on a patron's account. Test suspending and
  resuming holds.

TESTING TRANSLATABILITY

- Update a translation, e.g. fr-FR:

  > cd misc/translator
  > perl translate update fr-FR

- Open the corresponding .po file for JavaScript strings, e.g.
  misc/translator/po/fr-FR-messages-js.po
- Locate strings pulled from
  koha-tmpl/intranet-tmpl/prog/js/checkouts.js for
  translation, e.g.:

  msgid "Checked in"
  msgstr ""

- Edit the "msgstr" string however you want (it's just for
  testing).
- Install the updated translation:

  > perl translate install fr-FR

- Switch to your newly translated language in the staff client
  and repeat the test plan above. The translated strings should
  appear.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>