Bug 28641: ILLHiddenRequestStatuses does not consider custom statuses

Bug 28641: ILLHiddenRequestStatuses does not consider custom statuses

This patch adds the status_alias column to the ILLHiddenRequestStatuses sys pref check.
Because requests will have status_alias NULL by default, we also check for that.

Test plan:
Create multiple ILL requests of different backends and place them in different status (NEW, COMP, REQ, etc)
Create multiple ILLSTATUS entries
Add and remove a mix of both status and status_alias codes in ILLHiddenRequestStatuses and refresh the ILL requests page to confirm the result is according to expectation.

Sponsored-by: PTFS Europe
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>