Add NamedTransform support to ocioconvert

[doug-walker]

Named Transforms are an alternative to color spaces and are used in the new OCIO configs for ACES. It would be helpful if the OCIO command-line tool ocioconvert added an option to apply a NamedTransform. Note that there should be an option to apply it in either the forward or inverse direction.

[eli13gh]

Need a bit of learning curve but I can tackle this ask for ocioconvert, please assign it to me.

[pennelee]

Hi @doug-walker , Could you suggest a test that would show how the NamedTransform works?

[doug-walker]

@pennelee , please see this test. You basically ask for a NamedTransform object of the requested name from the config and then call getProcessor. Once you have the Processor, you can look elsewhere in ocioconvert to see how to apply pixels through it.