util: harden util.inspect

This makes sure values without prototype will still be inspected
properly and do not cause errors. It restores the original
information if possible.

Besides that it fixes an issue with boxed symbols: extra keys were
not visualized so far.

PR-URL: https://github.com/nodejs/node/pull/21869


Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>