Bug 33447: Make *->pickup_locations methods throw an exception on missing parameter

Bug 33447: Make *->pickup_locations methods throw an exception on missing parameter

This patch fixes the FIXME for making the methods throw an exception.

Tests are added, and POD is adapted as well.

To test:
1. Apply this patch
2. Run:
   $ ktd --shell
  k$ prove t/db_dependent/api/v1/patrons* \
           t/db_dependent/api/v1/holds.t \
           t/db_dependent/Reserves* \
           t/db_dependent/Hold* \
           t/db_dependent/Koha/Hold* \
           t/db_dependent/Items*

=> SUCCESS: Tests pass!
3. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>