console: improve console.group()

Preserve indentation for multiline strings, objects that span multiple
lines, etc.

also make groupIndent non-enumerable

Hide the internal `groupIndent` key a bit by making it non-enumerable
and non-configurable.

PR-URL: https://github.com/nodejs/node/pull/14999


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>