Bug 7317: Overload Koha::Illrequest::TO_JSON

Bug 7317: Overload Koha::Illrequest::TO_JSON

This patch implements an overloaded TO_JSON method, that introduces
the option to (selectively) embed information required on the REST
api.

Tests are included for the new method.

To test:
- Apply this patch
- Run:
  $ kshell
 k$ prove t/db_dependent/Illrequests.t
=> SUCCESS: Tests pass!
- Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Magnus Enger <magnus@libriotech.no>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Benjamin Rokseth <benjamin.rokseth@kul.oslo.kommune.no>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>