TrustAnchorIdentifier is MTC specific whereas BikeshedCertificate isn't #71
Description
In our BikeshedCertificate code we're careful to support non MTC certificates. Our TAI code however assumes we're dealing with MTCs as it always assumes the last segment is a batch number. We should either explicitly make BikeshedCertificate only work with MTC, or have TAIs not assume the MTC format.
Similarly in the latter case we should have LocalCAStore.Lookup take an TAI as argument (instead of RelativeOID), and figure out that for an MTC it should ignore the last segment.