Bug 27205: Check valid pickup location on POST /holds

Bug 27205: Check valid pickup location on POST /holds

This patch adds a check for valid pickup location to the POST /holds
route. A 400 code is returned if the supplied pickup library is not
valid.

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

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>