Bug 29508: Make GET /patrons/:patron_id use Koha::Patrons->search_limited

Bug 29508: Make GET /patrons/:patron_id use Koha::Patrons->search_limited

This patch makes the route return 404 if the user is not allowed to see
the requested patron information.

To test:
1. Apply the regression tests
2. Run:
   $ kshell
  k$ prove t/db_dependent/api/v1/patrons.t
=> FAIL: The code doesn't respect limits
3. Apply this patch
4. Repeat 2
=> SUCCESS: Tests pass!
5. 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: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>