Bug 24502: object.search also filter by prefetched columns

Bug 24502: object.search also filter by prefetched columns

This patch adds the possibility to object.search helper, to also filter by prefetched columns.

In order to dynamically add filter parameters, they must be coded as json and placed in the body of the request, coded as string in 'q' query parameter or as string in 'x-koha-query' header.

The coded json, is in fact dbix syntax.

To test:
1. apply this patch
2. prove t/Koha/REST/Plugin/Query.t t/db_dependent/Koha/REST/Plugin/Objects.t
3. Sign off

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>