Bug 20702: Add unit tests for GetHostItemsInfo

Bug 20702: Add unit tests for GetHostItemsInfo

Unfortunately, we did not have unit tests yet.
Adding some simple tests that test basic operation of the sub when the
pref is enabled/disabled and for MARC21/UNIMARC.

Test plan:
[1] Run t/db_dependent/Items/GetHostItemsInfo.t

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>