esm: refactor dynamic modules

This is a change from the ecmascript-modules fork.
There is no change to behavior and we would like to
upstream to reduce the delta between our repos.

Refs: https://github.com/nodejs/ecmascript-modules#9

PR-URL: https://github.com/nodejs/node/pull/24560
Refs: https://github.com/nodejs/ecmascript-modules/pull/9


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