perf_hooks: add missing resource timing attributes

[greenheadHQ]

Add the PerformanceResourceTiming attributes still missing from the Resource Timing spec: finalResponseHeadersStart, firstInterimResponseStart, renderBlockingStatus, contentType and contentEncoding. The getters follow the existing pattern in the file, and the WPT status file drops the ten idlharness subtests this makes pass.

Current values:

• finalResponseHeadersStart: same timing info field as responseStart
• contentType: '' (undici computes it in its report timing steps, but that path is currently unreachable since the request's initiator type is never set, and the reporting path that actually runs doesn't pass body info at all)
• contentEncoding: '' (spec default, not populated by the fetch side yet)
• firstInterimResponseStart: 0 (same)
• renderBlockingStatus: 'non-blocking' (same)

The getters pick up real values automatically once the producer side fills them in. Precedent: #51589 added deliveryType and responseStatus the same way.

responseStart now returns firstInterimResponseStart when it is non-zero, per the spec (no observable change, since nothing records interim response timings yet).

Refs: #51589

[nodejs-github-bot]

Review requested:

• @nodejs/web-standards

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.07%. Comparing base (31cde9f) to head (1037870).
⚠️ Report is 382 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65017      +/-   ##
==========================================
- Coverage   90.30%   90.07%   -0.24%     
==========================================
  Files         759      751       -8     
  Lines      247621   254817    +7196     
  Branches    46672    48095    +1423     
==========================================
+ Hits       223603   229514    +5911     
- Misses      15473    16487    +1014     
- Partials     8545     8816     +271     

Files with missing lines	Coverage Δ
lib/internal/perf/resource_timing.js	99.67% <100.00%> (+0.04%)	⬆️

... and 254 files with indirect coverage changes

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[greenheadHQ]

Hello @legendecas @jasnell 🖐️

Thank you for all the work that goes into reviewing contributions here! Just a gentle ping in case this PR slipped through the cracks. I would appreciate any feedback whenever you have time, no rush at all. Thanks!