Bug 29523: Pass the logged user around and use for validating

Bug 29523: Pass the logged user around and use for validating

In this patch I add 'user', containing the Koha::Patron object for the
logged in user in the params hash we pass around in to_api. I then use
that in a new 'is_accessible' method added to Koha::Patron.

The new method is really the equivilent of 'search_limited' in the plural
class and could perhaps be renamed 'is_limited' or something clearer for
the singular form 'is_filtered' or 'fitler_for_api' or something?

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>