module: simpler esm loading

This simplifies loading the experimental modules. Instead of always
checking for them we should eagerly load the functions in case the
experimental modules flag is passed through.

PR-URL: https://github.com/nodejs/node/pull/26974


Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Guy Bedford <guybedford@gmail.com>