Bug 25690: Make CanBookBeIssued return In Processing state as needing confirmation

Bug 25690: Make CanBookBeIssued return In Processing state as needing confirmation

This prevents checking out to a patron an item with hold to someone
else in the In Processing state via staff interface.

Also the checkout error message via SIP is now a more clearer one: "Item is
on hold for another patron." Before it was "Item cannot be issued:
$confirmation".

Also the branch transfer and batch checkout pages are adapted to this new
confirmation message as well.

To test:
 1) Create bib level hold to an item for patron A
 2) Check-in that item via SIP2, now the hold state should be "In processing"
 3) Apply patch
 4) Try to checkout the item to patron B via staff interface and
    notice we get now confirmation prompt do we really want to do it
    because it is in processing.

 In order to not have to setup SIP2 server, alternatively steps 1) and
 2) can be done so that you check-in the item in staff interface and
 make it Waiting, and then with SQL change it to "In processing":

 UPDATE reserves SET found = "P" WHERE reserve_id = XXX;
 UPDATE reserves SET waitingdate = NULL WHERE reserve_id = XX
 UPDATE reserves SET expirationdate = NULL WHERE reserve_id = XXX;

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>