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

Attention: 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 4 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.