vfs: allow imports without the node: prefix

[mcollina]

The experimental VFS module previously required the node: prefix. Allow both vfs and node:vfs in CommonJS and ESM while keeping --experimental-vfs gating unchanged.

The vfs module this shadow currently managed by @ljharb, who told me it's ok.

[nodejs-github-bot]

Review requested:

• @nodejs/loaders
• @nodejs/startup

[Renegade334]

Was there a consensus from the node:test TSC discussion against exposing any new barenamed core modules from now on, or am I making that up?

[panva]

The vfs module this shadow currently managed by @ljharb, who told me it's ok.

https://www.npmjs.com/package/vfs

Something doesn't add up here.

[JakobJingleheimer]

I think we should not do this

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.37%. Comparing base (ebef774) to head (8c31f00).
⚠️ Report is 277 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66414      +/-   ##
==========================================
+ Coverage   90.28%   90.37%   +0.09%     
==========================================
  Files         790      792       +2     
  Lines      271642   275682    +4040     
  Branches    51846    52854    +1008     
==========================================
+ Hits       245260   249156    +3896     
- Misses      16889    16939      +50     
- Partials     9493     9587      +94     

Files with missing lines	Coverage Δ
lib/internal/bootstrap/realm.js	96.98% <ø> (-0.01%)	⬇️

... and 194 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.