Color Management: add Filmic sRGB as an image colorspace

A typical use case is when you want to render with the Filmic view transform, but
composite an existing image in the background that should not be affected by the
view transform.

With this colorspace it's possible to do an inverse Filmic transform, render
everything in scene linear space, and then apply the Filmic transform again.

This is pretty basic in that this is not going to take into account the full view
transform including looks, curves and exposure. But it can be helpful anyway.

Ref T68926

release/datafiles/colormanagement/config.ocio

@@ -162,7 +162,7 @@ colorspaces:
     equalitygroup:
     bitdepth: 32f
     description: |
-      Standard RGB Display Space
+      sRGB display space
     isdata: false
     to_reference: !<FileTransform> {src: srgb.spi1d, interpolation: linear}
     from_reference: !<FileTransform> {src: srgb_inv.spi1d, interpolation: linear}
@@ -193,11 +193,11 @@ colorspaces:
 
   - !<ColorSpace>
     name: Filmic sRGB
-    family: display
+    family:
     equalitygroup:
     bitdepth: 32f
     description: |
-      Filmic sRGB view transform
+      sRGB displace space with Filmic view transform
     isdata: false
     from_reference: !<GroupTransform>
         children: