Add support for OpenColorIO (OCIO)

Description of the feature

OpenColorIO (OCIO) is a complete color management solution geared towards motion picture production with an emphasis on visual effects and computer animation. OCIO provides a straightforward and consistent user experience across all supporting applications while allowing for sophisticated back-end configuration options suitable for high-end production usage. OCIO is compatible with the Academy Color Encoding Specification (ACES) and is LUT-format agnostic, supporting many popular formats.

Use cases

As Krita[1], PhotoFlow[1] and Blender already supports OCIO it would be nice to have it in GIMP to to get an nice Workflow across all these applications.

[1] https://docs.krita.org/en/general_concepts/colors/color_managed_workflow.html [2] https://discuss.pixls.us/t/photoflow-ocio-and-aces/11293 [3] https://github.com/sobotka/filmic-blender