Outliner: Change All Scenes to Scenes and make it focus on compositing

We have different ways of explore the scene objects, namely View Layer and
Collections. This change let us focus on compositing elements only such as:

* View Layers
** Collections
** Render Passes
* Freestyle
* Grease Pencil?

Not included in this commit is an option to handle filtering of
collections passes, ... Not sure if we would like, though.
Since they are all properly nested under a "Collections" / "Passes"
parent.

source/blender/blenloader/intern/versioning_260.c

@@ -2454,14 +2454,14 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *main)
 						SpaceOops *so = (SpaceOops *)sl;
 
 						if (!ELEM(so->outlinevis,
-						          SO_ALL_SCENES,
+						          SO_SCENES,
 						          SO_GROUPS,
 						          SO_LIBRARIES,
 						          SO_SEQUENCE,
 						          SO_DATABLOCKS,
 						          SO_USERDEF))
 						{
-							so->outlinevis = SO_ALL_SCENES;
+							so->outlinevis = SO_SCENES;
 						}
 					}
 				}