Bug 22806: (follow-up) CanBookBeReserved and CanItemBeReserved must check AllowHoldsO...

Bug 22806: (follow-up) CanBookBeReserved and CanItemBeReserved must check AllowHoldsOnPatronsPossessions

As CanBookBeReserved() was failing as $patron and and $biblio were not
instantiated I fixed that up.

Test plan :
1 - set AllowHoldsOnPatronsPossessions to "Don't Allow"
2 - Checkout an item to a borrower
3 - Try to reserve an item using ILS-DI WebService -> Will work without complaining.
4 - Cancel the hold and apply patch
5 - Repeat 3 -> Should not place hold and show error "NotHoldable"

Sponsored-By: Catalyst IT
Signed-off-by: Laurence Rault <laurence.rault@biblibre.com>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>