v8: add cpu profile APIs

[theanarkh]

Add CPU profile APIs.

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[addaleax]

Suggested change

	classJSONOutputStream : publicv8::OutputStream {
	classJSONOutputStreamfinal: public v8::OutputStream {

[addaleax]

Btw – we may want to use HeapSnapshotStream here? I know it requires a bit more setup, but it integrates nicely with existing stream primitives in Node.js

[theanarkh]

I think these are two issues in HeapSnapshotStream:

1. We should not delete the snapshot(which is created in worker) in main thread.
2. It will crash when the worker exits.

constworker=require('worker_threads');constw=newworker.Worker("setInterval(() => {}, 100)",{eval: true})w.on('online',async()=>{conststream=awaitw.getHeapSnapshot()stream.on('data',()=>{});// Crashw.terminate();});

[szegedi]

Advocating for using CpuProfiler::Start and thus eliminating the need for users to invent names for the profiler sessions in order to use the API.

[codecov]

Codecov Report

❌ Patch coverage is 86.15385% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.95%. Comparing base (961554c) to head (1b66417).
⚠️ Report is 51 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_v8.cc	77.41%	2 Missing and 5 partials ⚠️
lib/v8.js	94.11%	2 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #59429 +/- ##
==========================================
+ Coverage 89.93% 89.95% +0.01% 
==========================================
Files 667 667 Lines 196775 196841 +66 Branches 38409 38422 +13 ==========================================
+ Hits 176977 177069 +92 + Misses 12247 12200 -47 - Partials 7551 7572 +21 

Files with missing lines	Coverage Δ
src/node_v8.h	40.00% <ø> (ø)
lib/v8.js	99.02% <94.11%> (-0.35%)	⬇️
src/node_v8.cc	79.84% <77.41%> (-0.59%)	⬇️

... and 51 files with indirect coverage changes

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