CVE-2020-25719 CVE-2020-25717 tests/krb5: Add tests for connecting to services anonym...

CVE-2020-25719 CVE-2020-25717 tests/krb5: Add tests for connecting to services anonymously and without a PAC

At the end of the patchset we assume NT_STATUS_NO_IMPERSONATION_TOKEN if
no PAC is available.

For now we want to look for ACCESS_DENIED as this allows
the test to pass (showing that gensec:require_pac = true
is a useful partial mitigation).

This will also help others doing backports that do not
take the full patch set.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14801
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14799
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14561
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14556

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>