http2: add diagnostics_channel for client session and streams

[tmm1]

Adds diagnostics similar to http/undici, to enable integration into network inspector protocol

cc #53946 (comment)@cola119

[nodejs-github-bot]

Review requested:

• @nodejs/http2
• @nodejs/net

[RaisinTen]

Good to see you contributing to Node.js Aman :)
The new diagnostic channels need to be documented and this also needs some tests.
You can see #55622 for reference.

[codecov]

Codecov Report

❌ Patch coverage is 35.48387% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.26%. Comparing base (25842c5) to head (5e15a34).
⚠️ Report is 757 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/http2/core.js	35.48%	18 Missing and 2 partials ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #57955 +/- ## ========================================== - Coverage 92.26% 90.26% -2.00%  ========================================== Files 325 630 +305 Lines 126673 186155 +59482 Branches 20783 36478 +15695 ========================================== + Hits 116869 168035 +51166 - Misses 9576 11000 +1424 - Partials 228 7120 +6892 

Files with missing lines	Coverage Δ
lib/internal/http2/core.js	95.10% <35.48%> (-0.39%)	⬇️

... and 412 files with indirect coverage changes

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[Flarna]

I think the new diagnostics channels should be mentioned in doc somewhere including stability level and version when they were added. e.g. see https://nodejs.org/docs/latest/api/diagnostics_channel.html#built-in-channels

[Qard]

As already stated, needs docs.

Also, might be better to put the created channel publishes in the ClientHttp2Stream and ClientHttp2Session constructors. Looks like some other logic is not being included in that window.

[tmm1]

In researching this further, I discovered significant prior art by the nodesource team:

nodesource/nsolid@6350b95
nodesource/nsolid@63a9b6f

They are amenable to having this work upstreamed, so I am going to revamp my PR to pull in those commits and flesh it out with docs and tests.

[RaisinTen]

As discussed privately with Aman, I'll send separate PRs for this with tests and docs. Starting with #58246.

[RaisinTen]

Next one: #58292

[RaisinTen]

Another one #58306

[RaisinTen]

#58317 and #58329 for client stream finish and close respectively