Bug 31069: Remove ExplodedTerms dependency on templates

Bug 31069: Remove ExplodedTerms dependency on templates

This patch removes the use of templates and CGI in ExplodedTerms by using the
Koha::I18N library.

The functionality on the package is too simple, and messing with the
template paths complexity on the tests was too much, given we have a
nice way to have translatable strings at the package level.

This patch does that, and cleans up the test file as well, that required
complex template and CGI mocking to run properly.

To test:
1. Run:
   $ kshell
  k$ prove t/db_dependent/SuggestionEngine_ExplodedTerms.t
=> FAIL: It fails in master
2. Apply this patch
3. Repeat 1
=> SUCCESS: Tests pass
4. Follow the original test plan
=> SUCCESS: Things work
5. Enjoy the rest of the day and forget this ever happened

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>