IPA: Add the options that the IPA subdomains code will read for trusted domains on the client
With this patchset, IPA clients will read and evaluate the ad_server and
ad_site options. This patch just adds the required structures for later
usage.
Related:
https://pagure.io/SSSD/sssd/issue/3291
Reviewed-by: Sumit Bose <sbose@redhat.com>