Bug 32982: Add primary button to libary group modals

Bug 32982: Add primary button to libary group modals

This patch updates the New and Edit group modals in the library groups
admin page to have a primary 'Save'/'Update' button and a default
'Cancel' button.

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 9729621c1d8bf2573e7b7d08a69e6ef572b3388d)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>