restricted item shown as nonexistent when not logged in

[milanmajchrak]

PRs:
dataquest-dev/dspace-angular#612
#646

In v5, when item is restricted, link says item is restricted and sign-in is needed.
in v7, classic 404 appears, saying the link is wrong. (But after login, item is shown, on the same link)

example:

https://dev-5.pc:8443/handle/11234/1-2907