Bug 35091: Improve translation of usage statistics country list

Bug 35091: Improve translation of usage statistics country list

This patch reworks country-list.inc so that each country name can be
wrapped separately in the t() translation function and be processed
individually during the translation process.

To test, apply the patch and update a translation, e.g. fr-FR:
   - perl misc/translator/translate update fr-FR

- Edit the updated po file for the language you chose, e.g.
  misc/translator/po/fr-FR-messages.po, and locate strings from
  country-strings.inc. Each country names should show up as a separate
  string for translation.
- Update the file to fill in translated strings for one or more
  countries. For example:

  koha-tmpl/intranet-tmpl/prog/en/includes/country-list.inc:2
  msgid "Afghanistan"
  msgstr ""

- Install the updated po file:
   - perl misc/translator/translate install fr-FR
- Enable the translation if necessary under Administration -> System
  preferences -> language.
- Go to Administration -> Share usage statistics and check the "Your
  country" dropdown. The list should look correct.
- Switch to your updated translation and confirm that the country names
  you translated show up as expected.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>