Bug 15380: Move Koha::Authority to Koha::MetadataRecord::Authority

Bug 15380: Move Koha::Authority to Koha::MetadataRecord::Authority

The existing Koha::Authority does not use Koha::Objects and does not
exclusively deal with DB objects.
It makes much sense to move it to let the space free for a
Koha::Authority and Koha::Authorities modules based on Koha::Object.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com