Bug 17501: Use Koha::Object in Koha::Upload::_register

Bug 17501: Use Koha::Object in Koha::Upload::_register

The _register routine basically inserts a new record in uploaded_files.
It should use Koha::UploadedFile now.

Test plan:
[1] Run t/db_dependent/Upload.t
[2] Upload a file via Tools/Upload.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>