Linked work items show error when they belong to SAML groups that require a fresh authentication

It was discovered in #267956 that we are getting an error on the tasks list of the detail issue view

This is happening because the linked item belongs to a group that enforces SAML authentication. So, in the GraphQL API when we try to fetch information for the linked item, we will get NULL on the workItem field because of the authorization framework and because the field is declared as not nullable.

Possible solutions

We should probably change the field to be nullable to avoid this error, then we can probably display a message saying that there's a linked item that requires authentication before it can be displayed. We do something similar in the todos view https://gitlab.com/dashboard/todos when we detect one of the listed items requires a new authentication with the group