Bug 24228: Add parameters to Koha::Object(s)->to_api to automatically embed objects

Bug 24228: Add parameters to Koha::Object(s)->to_api to automatically embed objects

This patch makes Koha::Object(s)->to_api have an 'embeds' parameter that
using dot notation (e.g. resource.related_resource.another_one) allows
embedding objects recursively.

To test:
1. Apply this patch
2. prove t/db_dependent/Koha/Object.t

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Agustin Moyano <agustinmoyano@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>