Bug 29754: Unit test

Bug 29754: Unit test

This adds a unit test to the SIP code

It also adds some spacing and dividers to make the tests for 'relationships_debt' easier to read

To test:
prove -v t/db_dependent/Koha/Patron.t - passes and is readable
prove -v t/db_dependent/SIP/Patron.t - fails

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>