Bug 29706: Hide items that cannot be held by default when placing hold on OPAC

Bug 29706: Hide items that cannot be held by default when placing hold on OPAC

This patch adds a 'holdable' and 'unholdable' class to the rows of the table

Additionally I rename the 'backgroundcolor' field to 'onloan' as that is what it contains.
Note: Out of the box, there is no css associated with this class

I add a div around the table to allow hiding the new buttons as well when optiuons are hidden

It would be nice in the future to utilise a Koha table here, however, it is complicated by multi-holds

To test:
 1 - Add a number of items to a record, ensuring they belong to different libraries
 2 - Set 'Default checkout, hold and return policy'->'Hold policy' to 'From home library'
 3 - Sign in to opac and attempt to placehold on the record
 4 - Click 'show more options' and 'a specificitem'
 5 - Note holds table includes items that cannot be held
 6 - Apply patch
 7 - Reload holds page
 8 - Note items that cannot be heldare hidden
 9 - Click 'Show unholdable items' and note they appear
10 - Click 'Hide unholdable items' and veriofy they hide
11 - Test with multi holds

Signed-off-by: The Minh Luong <the-minh.luong@inlibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>