util: move inspect in separate file

The inspect function became very big and it's better to handle this
in a separate file.

PR-URL: nodejs#22845
Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>