Bug 33245: Introduce patron->is_active

Bug 33245: Introduce patron->is_active

Does only add the new patron method.

NOTE: We may define additional criteria at some point, but I think
that this is a good starting point.

Test plan:
Run perl -MKoha::Patron -e'print Koha::Patrons->find(X)->is_active(Y);'
Note: replace X by a valid borrowernumber and Y by date criterium.

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