test: update FileAPI tests from WPT

[Ms2ger]

Notably, the test_blob() helper functions no longer uses FileReader, so tests using them can now run successfully in node.

[nodejs-github-bot]

Review requested:

• @nodejs/web-standards

[Ms2ger]

I noticed another bug in the implementation while looking at the remaining failures here, for which I submitted tests upstream. I've added those to this PR as well.

The CI failures seem to be caused by the github outage yesterday.

[github-actions]

Failed to start CI

   ⚠  Commits were pushed since the last approving review:
   ⚠  - test: update FileAPI tests from WPT
   ⚠  - fixup! test: update FileAPI tests from WPT
   ✘  Refusing to run CI on potentially unsafe PR

https://github.com/nodejs/node/actions/runs/21860435679

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.74%. Comparing base (ae2ffce) to head (4714dbc).
⚠️ Report is 49 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61750      +/-   ##
==========================================
- Coverage   89.75%   89.74%   -0.01%     
==========================================
  Files         674      675       +1     
  Lines      204416   204642     +226     
  Branches    39285    39322      +37     
==========================================
+ Hits       183472   183666     +194     
- Misses      13227    13262      +35     
+ Partials     7717     7714       -3     

see 52 files with indirect coverage changes

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[joyeecheung]

RSLGTM

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/71288/