Check for graph link for Azure AD

Azure AD can refuse to send `memberOf` if the number of groups exceeds 150. See this article: https://docs.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-fed-group-claims. It includes an attribute named `http://schemas.microsoft.com/claims/groups.link` if this substitution is made. We should check for this and report on it.