module: expose module format by module loader

[legendecas]

Module loaders may change a requested module format. It is not safe to
determine a .js format by package.json#type as well. Expose a helper
function to frameworks that load js files to avoid relying on
import/require failover-and-retry.

Taking mocha as an example: https://github.com/mochajs/mocha/blob/b0c269616e775689f4f28eedc0a9c5e99048139b/lib/nodejs/esm-utils.js#L41-L53.

import has a different resolution method compared to require. So mocha
relies on import and failover to require. But this approach fails when
--experimental-strip-types is enabled by default. For a legacy TypeScript
module file, its module syntax should not be depended on. And in the case
of mochajs/mocha#5314, given that strip-types is
enabled, the error becomes SyntaxError and the failover bails out.

Frameworks like mocha should take advantage of Node.js module format
detection (including custom loaders) to use import or require
deterministically.

[nodejs-github-bot]

Review requested:

• @nodejs/loaders
• @nodejs/typescript

[aduh95]

I have a WIP for that in #55756

[legendecas]

I have a WIP for that in #55756

Ah, that's cool! Would you mind adopting tests in this PR as well?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.26%. Comparing base (8456a12) to head (07f897a).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #57777      +/-   ##
==========================================
+ Coverage   90.23%   90.26%   +0.03%     
==========================================
  Files         630      630              
  Lines      185245   185253       +8     
  Branches    36301    36307       +6     
==========================================
+ Hits       167154   167223      +69     
+ Misses      11006    10982      -24     
+ Partials     7085     7048      -37     

Files with missing lines	Coverage Δ
lib/internal/modules/esm/formats.js	98.92% <100.00%> (+0.27%)	⬆️
lib/internal/modules/esm/loader.js	95.18% <100.00%> (+0.14%)	⬆️
lib/module.js	100.00% <100.00%> (ø)

... and 43 files with indirect coverage changes

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[marco-ippolito]

LGTM thanks for working on this ❤️