Rather than a `L` (linked), `O` (overridden) or `M` (missing) prefix for the
name, show the existing library status icons. See D7999 for screenshots.
Note that when using preview icons, or if the search menu contains items with
own icons (e.g. brush icons), we still fallback to the prefix solution.
Zero or fake user is still indicated with a prefix.
Differential Revision: https://developer.blender.org/D7999
Reviewed by: Bastien Montagne, William Reynish
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