doc: update WPT test runner README.md

[panva]

• Rewrite introduction; remove outdated test-whatwg-* note and redundant "How it works" section
• Document full WPTRunner API (concurrency, setFlags, setInitScript, setScriptModifier, pretendGlobalThisAs)
• Switch all examples from JSON to CJS
• Document wildcard * patterns in status file keys
• Document inspector as a supported requires value
• Add "Daily WPT report" section with wpt.fyi dashboard link

[nodejs-github-bot]

Review requested:

• @nodejs/web-standards

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.93%. Comparing base (de5644c) to head (019f97b).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62680      +/-   ##
==========================================
- Coverage   89.81%   88.93%   -0.89%     
==========================================
  Files         699      699              
  Lines      216235   216235              
  Branches    41336    41246      -90     
==========================================
- Hits       194216   192302    -1914     
- Misses      14129    15970    +1841     
- Partials     7890     7963      +73     

see 105 files with indirect coverage changes

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[aduh95]

Do we mean to encourage use of CJS over JSON? Shouldn't we give the two examples?

Suggested change

	For example, to add the URL tests, add a `test/wpt/status/url.cjs` file.
	For example, to add the URL tests, add a `test/wpt/status/url.json` or `test/wpt/status/url.cjs` file.

[panva]

Do we mean to encourage use of CJS over JSON?

For the features available, yes. As it is much less destructive wrt to WPT status file backports to avoid switching from json to cjs as much as possible.