Check `full_range_flag` on alpha auxiliary images

MIAF ISO/IEC 23000-22:2019/Amd. 2:2021 § 7.3.5.2 adds the following requirement:
> — Given the semantics above, if a CICP colour property is associated with an alpha auxiliary image item, full_range_flag shall be set to 1.

Currently we don't check for any `colr` properties associated with alpha auxiliary image items