util: inspect __proto__ key as written in object literal

Since util.inspect() gives object-literal-like output, handle the
special `__proto__` key in the way that it would be handled in object
literals.

PR-URL: https://github.com/nodejs/node/pull/37713


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>