Bug 21083: Handle repeatable patron attributes in batch patron modification tool

Bug 21083: Handle repeatable patron attributes in batch patron modification tool

This patch adds the ability to set patron attributes marked as
repeatable in the batch patron modification tool.
Prior to this patch they were ignored.

Test plan:
You should try with several combinaisons and set patron attributes using
the batch patron modification tool.
Make sure there is no data lose and that the result is what you expect
Please detail in a comment what you tested.

Signed-off-by: Philip Orr <philip.orr@lmscloud.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>