Bug 4319: [OPAC] Allow holds on waiting/transit items

Bug 4319: [OPAC] Allow holds on waiting/transit items

Test plan:

 - Checkout an item
 - Place hold on this item,
 - Return the item
 - Make sure the hold is waiting (found W) and AllowOnShelfHolds is
   not to 'Allow'
 - Check that the button "Place hold" appears in opac detail page of
   the biblio

 - do the samewith items/reserves in transit

Changes on C4::Reserves::IsAvailableForItemLevelRequest

Make sure this tests pass:
  - t/db_dependent/Reserves.t
  - t/db_dependent/Holds/DisallowHoldIfItemsAvailable.t

Rebased - 2017-12-12 - Alex Arnaud

Bug 4319 - [QA fix] Create Koha::Biblio->hasItemswaitingOrInTransit

Signed-off-by: Jon Knight <J.P.Knight@lboro.ac.uk>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>