Bug 26956: Allow guarantor's controls to be set when a guarantee is created

Bug 26956: Allow guarantor's controls to be set when a guarantee is created

With AllowStaffToSetCheckoutsVisibilityForGuarantor and
AllowStaffToSetFinesVisibilityForGuarantor set to Allow, one can only see the
controls for these values in the patron record *after* the patron has been saved
with a guarantor. That makes a frustrating 2-step process. We should be able to
set those values regardless of whether or not there is currently a guarantor on
the account.

Test plan:
Create a guarantee and confirm that the 2 options "Show checkouts to
guarantors" and "Show fines to guarantors" are displayed
Select Yes, save
Confirm that the values have been correctly saved

Signed-off-by: Kelly McElligott <kelly@bywatersolutions.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>