Bug 30125: Add full-stack tests for API pagination

Bug 30125: Add full-stack tests for API pagination

This patch adds tests for all the pagination use cases on a real route
(GET /cities). It tests _page, _per_page along with the returned Link
headers and total counts (i.e. X-Total-Count, X-Base-Total-Count), and
the results themselves.

To test:
1. Apply this patch
2. Run:
   $ kshell
  k$ prove t/db_dependent/api/v1/pagination.t
=> SUCCESS: Tests pass!
3. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>