src: add event loop based metrics into node

[pabloerhard]

Adds an opt in into monitorEventLoopDelay(), this option adds support for per iteration sampling using libuv hooks, while preserving the existing timer based approach.

When the new samplePerIteration option is set to true, monitorEventLoopDelay() samples directly from event loop iterations instead of using the interval timer. When samplePerIteration is omitted or false, the existing interval based implementation remains unchanged, including resolution handling and the older interval based trace counters.

Motivation
The interval based implementation has two limitations that the new option addresses:

• Inaccurate measurements. Delay was approximated from a timer dispatch jitter (RecordDelta() between timer ticks) rather than measured from the loop itself. Samples had an implicit floor of resolution ms and could miss delays that didn't happen to coincide with a timer tick.
• Wasteful wake ups. The timer forced the event loop to iterate every resolution ms just to record a sample, even when the application was otherwise idle and no one was reading the histogram.

This is an alternative implementation to the one in #62934

This PR directly addresses the following issue #56064

[addaleax]

This should call the superclass's method instead of duplicating it

[pabloerhard]

Calling HandleWrap::Close() would just uv_close check_handle_ immediately, run HandleWrap::OnClose and treat the wrap as fully torn down.

This would leave prepare_handle_ on need of a uv_close, so you’d risk a libuv handle leak or teardown in the wrong order relative to HandleWrap’s lifecycle.

[pabloerhard]

Hi @addaleax , I initially misunderstood your comment. I've refactored the Close method to use the superclass Close method instead of duplicating the shared logic.

[codecov]

Codecov Report

❌ Patch coverage is 78.51852% with 29 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.64%. Comparing base (80e0f14) to head (27ead1e).
⚠️ Report is 109 commits behind head on main.

Files with missing lines	Patch %	Lines
src/histogram.cc	79.50%	11 Missing and 14 partials ⚠️
src/histogram.h	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62935      +/-   ##
==========================================
- Coverage   89.65%   89.64%   -0.02%     
==========================================
  Files         708      708              
  Lines      220413   220546     +133     
  Branches    42275    42290      +15     
==========================================
+ Hits       197607   197702      +95     
- Misses      14658    14675      +17     
- Partials     8148     8169      +21     

Files with missing lines	Coverage Δ
lib/internal/perf/event_loop_delay.js	95.95% <100.00%> (+0.12%)	⬆️
src/node_perf.cc	86.61% <100.00%> (+0.22%)	⬆️
src/histogram.h	50.00% <0.00%> (-10.00%)	⬇️
src/histogram.cc	79.08% <79.50%> (+0.12%)	⬆️

... and 33 files with indirect coverage changes

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