src: changing node_file's usage of v8::Resolver

node_file was casting back and forth between v8::Resolver and
v8::Promise. This is unnecessary; most of the time it just wants the
v8::Resolver, converting to the v8::Promise only as a return value.

PR-URL: https://github.com/nodejs/node/pull/18765


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Kyle Farnung <kfarnung@microsoft.com>