Bug 30058: Add Koha::Patrons->filter_by_have_subpermission

Bug 30058: Add Koha::Patrons->filter_by_have_subpermission

This method will allow to filter a patron set by a given subpermission.
It will be useful on bug 30055 where we want to display only patron
with suggestion or acquisition subpermission.
Note that it could be extended to allow several subpermissions, but we
don't need it so far.

Test plan:
  prove t/db_dependent/Koha/Patrons.t
must return green

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>