assert: improve the strict equal messages

In case reference (un)equal objects fail in assertion, it should be
clear that it is about the reference equality and not about the
object properties. This is fixed by improving the message in such
cases.

Refs: https://github.com/nodejs/node/issues/22763

PR-URL: https://github.com/nodejs/node/pull/23056
Refs: https://github.com/nodejs/node/issues/22763


Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>