modules: remove file extension and directory resolving for esm

[MylesBorins]

this build on top of the limitations of the package name map proposal.
It removes file extensions and directory resolution in the resolver.

This is only currently limited for local development. When resolving
dependencies file extension and directory resolution will still work.

Refs: https://github.com/domenic/package-name-maps

Moved from nodejs/node#21729

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[devsnek]

i'd like to make sure we have this repo set up to automatically pull updates from nodejs/node before we're merging changes

[bmeck]

We have people discussing the continues use of bundlers in #1 and not focusing on web compatibility since they can continue to use the solutions bundlers provide. If that is the mentality we don't need to do this PR since resolution could be provided by ahead of time tools like bundlers.

Additionally, given the package name maps approach and proof of creating maps that support index files, extension completion, etc. I don't see the need for this PR even with people wanting to use bundlers if they want to manually make package name maps, or using a different tool.

[MylesBorins]

Closing in lieu of #6