Bug 12556: Add new "in processing" state to holds

Bug 12556: Add new "in processing" state to holds

This adds new syspref, HoldsNeedProcessingSIP, which controls whether
a hold that is related to item will be filled automatically or not. If
the user has enabled the syspref then instead of fulfilling the hold
automatically the hold will go to "in processing" state.

To test:
 1. Checkout a book to patron A
 2. Place a bib level hold to the book for B
 3. Patron A returns the book via SIP, to simulate this use:
        ./misc/sip_cli_emulator.pl -su koha -sp koha -l CPL -a 127.0.0.1 -p 6001 --item <ItemBarcode> -m checkin
 4. Notice that no notification is generated for Patron B about hold
    and that the hold status in intranet and opac is "In Processing".
 5. Notice that patron A (or other patrons) cannot checkout a book
    that is in processing, because it is considered to be attached to
    the holdee (similarly to the waiting state):
        ./misc/sip_cli_emulator.pl -su koha -sp koha -l CPL -a 127.0.0.1 -p 6001 --patron <PatronABarcode> --item <ItemBarcode> -m checkout

Signed-off-by: Timothy Alexis Vass <timothy_alexis.vass@ub.lu.se>
Rebased-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>