Bug 30244: Include lost items in list of hidden items

Bug 30244: Include lost items in list of hidden items

When building search results for XSLT we generate and pass a list of hidden
itemnumbers.

We do skip the lost items in our parsing, however, we neglect to add the itemnumber
to the hidden list

This patch simply adds the lost itemnumbers to the list

There is more work to be done here to simpliofy this process, however, this patch resolves
the issue and can be backported to stable branches

To test:
1 - Set systempreference hidelostitems to "Don't show"
2 - Edit a record to set one item as lost and one as available
3 - Perform an OPAC search that returns the record above
4 - Note that the lost item shows in availability line
5 - Click on the record - note the lost item does not show on details
6 - Apply patch
7 - Reload search results
8 - Lost itme no longer displays

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>