Bug 23154: Add pagination to /api/v1/checkouts

Bug 23154: Add pagination to /api/v1/checkouts

Allow to use _page and _per_page query parameters for
/api/v1/checkouts
Also fix a timezone problem in t/db_dependent/api/v1/checkouts.t

Test plan:
1. With your favorite REST tester tool, or directly in the browser,
   fetch http://koha/api/v1/checkouts and check that you have results
2. Fetch /api/v1/checkouts?_per_page=1&_page=1 and check that only the
   first result is returned. Check that response contains headers
   X-Total-Count and Link
3. Fetch /api/v1/checkouts?_per_page=1&_page=2 and check that only the
   second result is returned. Check that response contains headers
   X-Total-Count and Link
4. prove t/db_dependent/api/v1/checkouts.t

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>