Bug 8438: Users can only claim for serials related to their branch.

Bug 8438: Users can only claim for serials related to their branch.

Only superlibrarian users and users with superserials permission
can override this limitation.

This patch adds a new subroutine C4::Serials::can_claim_subscription.

Signed-off-by: Paola Rossi <paola.rossi@cineca.it>
The upgrading of the DB was as required:
for each [PT/S] patron with the permission "claim_serials" ON,
the permission "superserials" became[/was kept to] ON.

Then, after having checked the DB upgrading, to test the currently
adding limitation:
> Users can only claim for serials related to their branch
, I reset 2 PT/S patrons-users to:
permission claim_serials: YES
permission superserials: NO
and I set the syspref "IndependendeBranches" to "Prevent".

For:
> Only superlibrarian users can override this limitation.
the S patron-user could list AND claim:
A) subscriptions of his own branch,
B) subscriptions of other branch,
C) subscriptions without branch.

For:
> Only users with superserials permission can override this limitation.
the PT patron-user could list:
A) subscriptions of his own branch,
B) subscriptions of other branch,
C) subscriptions without branch,
and could claim only:
A) subscriptions of his own branch,
C) subscriptions without branch.

NB: a subscription is selected to be claimed.

Then I set the syspref "IndependendeBranches" to "Don't prevent".
The behaviour was [exactly the same as in master] without the added
limitation.

On [S/PT] patrons, if permission claim_serials was NO, no Claims
link was available on Serials' page, either under "Prevent" or under
"Don't prevent".

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Added the results of Paola's testing to the commit message
as test plan.

Note to RM: Maybe we could add a note to the release notes, that
Koha now enforces superserials with independent branches better,
so people might have to adapt permissions in order to claim
for other branches.
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>