Bug 14385: Extend OpacHiddenItems to allow specifying exempt borrower categories

Bug 14385: Extend OpacHiddenItems to allow specifying exempt borrower categories

Edit: Fixing merge conflicts in
 - t/db_dependent/Items.t
 - t/db_dependent/Search.t
 - C4/Search.pm

Changes the API for calling GetHiddenItems and all the places in the code that call it. This is to allow borrower categories to be passed in.
Adds an OpacHiddenItemsExceptions syspref to allow certain borrower categories to be able to see items, even if they are marked hidden by OpacHiddenItems

To test:

1) Make two borrowers, one in a category that should see everything (ie Adult), and another in a category that should only see certain things (ie Adult - exceptions)
2) Add the borrower that can see everything (the Adult) to OpacHiddenItemsExceptions
3) To the OpacHiddenItems syspref, add an item type (ensure that you have some records that fall under this type in your library).
4) Log in as the borrower that should only see certain things (Adult - exception)
5) Do a search, filtered to show records which are the item type that you specified in the OpacHiddenItems syspref. No records should show for this borrower as this item type is hidden to them.
6) Log in as the borrower that should see everything (Adult)
7) Do the same search. There should be results from this search, as this borrower category has been specified as an exception to the hidden items

Signed-off-by: Claire Gravely <c.gravely@arts.ac.uk>

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>

Signed-off-by: Aleisha Amohia <aleishaamohia@hotmail.com>

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>