Bug 22701: Unit tests for Koha::Biblio->items

Bug 22701: Unit tests for Koha::Biblio->items

This patch adds tests fr the current items() implementation. The idea is
to verify no behaviour change takes place after we make it us
_new_from_dbic instead of calling Koha::Items->search.

To test:
- Run:
  $ kshell
 k$ prove t/db_dependent/Koha/Biblio.t
=> SUCCESS: Tests pass!
- Sign off :-D

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>