Color management: Add AgX view transform and make it default

On a user level this view transform provides much better handling of colors in
the over-exposed areas.

With this configuration the following display devices are available, including
AgX view transform for them:
* sRGB
* Display P3
* Rec.1886
* Rec.2020

NOTE: There is no Filmic view transform available for the newly added display
devices.

AgX also brings an implementation of False Colors view transform, which replaces
Filmic-based, and is available for all display devices.

The backward compatibility is preserved. The new files will default to AgX view
transform, which makes it non-forward compatible.

More technical details is available in the original PR #106355.
Please note that the PR has been split into more incremental changes when
was landing.

Pull Request: https://projects.blender.org/blender/blender/pulls/111099

tests/python/bl_imbuf_save.py

@@ -65,6 +65,10 @@ class ImBufTest(AbstractImBufTest):
 
         # Save the image in the desired format with the desired settings
         scene = bpy.data.scenes[0]
+
+        # The reference images were saved using Filmic view transform.
+        scene.view_settings.view_transform = "Filmic"
+
         ref_image_path = self.reference_dir.joinpath(img.name)
         out_image_path = self.output_dir.joinpath(img.name)
         img.save_render(str(out_image_path), scene=scene)