Missing Channel Ordering ARGB

OCIO is currently missing channel ordering ARGB.
This is the default channel ordering Qt uses. Having this would be nice to have as it would benefit without having to shuffle channels when color managing [Qt Images](https://doc.qt.io/qt-6/qimage.html#image-formats:~:text=while%2032%2Dbit%20images%20store%20ARGB%20values%20directly.).