Add the new 'renewals' relation to Koha::Old::Checkout to return a
list of Koha::Checkouts::Renewal objects.
We also add the same relation to the OldIssue schema inline.
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>