Bug 38166: Make core status graph strings translatable

Bug 38166: Make core status graph strings translatable

This patch makes several strings translatable. I usually dealth with
this by adding my statuses like `NEW` to the status graph shippped by
the backend I was working with, and solved the translation step inside
of the plugin itself.

But really, the core status graph should be translatable so core
backends (like the to-be FreeForm) and backend authors can rest assured
they only need to care about their custom statuses.

To test:
1. Make sure you have 35570 applied so it is easier to test
2. Enable the ILLModule syspref.
3. Install a language you're familiar with. I pick es-ES for the sake of
   this testing steps to be readable:
   $ ktd --shell
  k$ koha-translate --install es-ES --dev kohadev && restart_all
4. Enable (language sysprefs) and switch to your language (click at the
   left bottom on the language name).
5. Create a new ILL request
=> FAIL: Notice some buttons are not in your language
6. Jump to the ILL requests list
=> FAIL: The status displays as 'New request'
7. Apply this patch
8. Generate the translation entries for the core status graph strings:
  k$ gulp po:extract
  k$ gulp po:update # I had to run it twice to complete, unrelated error
9. Edit the relevant -messages.po file. In my case:
  k$ vim misc/translator/po/es-ES-messages.po
Note: it is easier on VScode which shows you the changed lines in colors
on the scroll bar. The idea is to find the new strings that relate to
Koha::ILL::Request and translate them
10. Translate the strings that relate to this patch (at least 'New
    request' and some of the buttons in the ILL request detail).
11. Install the new translations:
  k$ koha-translate --update es-ES --dev kohadev && restart_all
12. Refresh the ILL requests list
=> SUCCESS: The request status is translated!
13. Manage the ILL request
=> SUCCESS: The buttons you translated, are translated!!
14. Sign off :-D
15. Grant tcohen some cookies next time

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Pedro Amorim <pedro.amorim@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>