Bug 37522: Logging item modification should record the original version of the item

Bug 37522: Logging item modification should record the original version of the item

When modifying bibliographic record, Koha records in the log the
original version of the record.  This allows one to see what has been
changed in the record.

However, in case of item modification Koha records in the log the the
current version of the item (i.e. the version after the edit).  This is
inconsistent with the biblio modification behavior and makes it
difficult or even impossible to trace changes (especially in case of the
first modif since the initial version is not being recorded).

This patch makes the item modification logging feature work similarly to
logging modifications in bibliographic records.

Test plan:
==========
1. With CataloguingLog enabled (default in ktd) make a modification of
   an item.
2. Check the Modification log.  You should see as the recorded version
   the version of the item after the modification.
3. Apply the patch; restart_all.
4. Repeat p. 1.
5. In the Modification log you should see now the version of the item
   that existed before the recent modification.

Sponsored-by: Ignatianum University in Cracow
Signed-off-by: Roman Dolny <roman.dolny@jezuici.pl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>