Bug 21011: Search for items with not defined homebranch and/or holdingbranch

Bug 21011: Search for items with not defined homebranch and/or holdingbranch

From bug 5789: scripts can fail if items.homebranch and/or
items.holdingbranch is not defined

This script will help people catching these migration issues.

Test plan:
Update your items table to set some homebranch or holdingbranch to NULL
Run this script
It will display the different items with not defined values in these
fields.

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>