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

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

The _lookup routine performs a few select statements on uploaded_files.
In this patch the SQL statements are replaced with Koha::Object calls.
One call of _lookup is replaced directly by Koha::UploadedFiles.

Note: _lookup can be removed in a later stage.

Test plan:
[1] Run t/db_dependent/Upload.t
[2] Upload a file in some upload category
[3] Try to upload the same file into the same category. Error?
[4] Try to upload the same file in another category. Should work.

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>