clutter/color-state: Add transfer function

Another enum, defining SRGB gamma transfer function, and the PQ transfer
function. As with color spaces, add a 'default' that for now is treated
as if it was sRGB.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3433>

clutter/clutter/clutter-actor.c

@@ -17838,7 +17838,8 @@ create_default_color_state (ClutterActor *self)
 {
   ClutterColorState *color_state;
 
-  color_state = clutter_color_state_new (CLUTTER_COLORSPACE_DEFAULT);
+  color_state = clutter_color_state_new (CLUTTER_COLORSPACE_DEFAULT,
+                                         CLUTTER_TRANSFER_FUNCTION_DEFAULT);
 
   return color_state;
 }