Bug 28078: Add 'ignore_hold_counts' param to CanItemBeReserved

Bug 28078: Add 'ignore_hold_counts' param to CanItemBeReserved

This patch adds an optional param 'ignore_hold_counts' to the routine, while still forbidding holds when 0 are allowed

To test:
1 - prove -v t/db_dependent/Holds.t

Signed-off-by: David Nind <david@davidnind.com>
JK: Commit message amended: Fixed title formatting
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit d3adcec676f97a1456dbb072479a99f7224e724c)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>