http2: emit session close before stream close

[mcollina]

Fixes: #63412

This changes the HTTP/2 session shutdown path so that when the transport has
already been closed, the client session 'close' event is queued before stream
close callbacks are scheduled.

That gives clients a race-free chance to invalidate cached
ClientHttp2Session instances before stream 'close' handlers try to reuse
that session and synchronously hit ERR_HTTP2_INVALID_SESSION.

[nodejs-github-bot]

Review requested:

• @nodejs/http2
• @nodejs/net

[codecov]

Codecov Report

❌ Patch coverage is 96.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.06%. Comparing base (debe2ed) to head (0984bca).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/http2/core.js	96.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #63414      +/-   ##
==========================================
+ Coverage   90.05%   90.06%   +0.01%     
==========================================
  Files         714      714              
  Lines      225742   225765      +23     
  Branches    42727    42723       -4     
==========================================
+ Hits       203285   203335      +50     
+ Misses      14234    14230       -4     
+ Partials     8223     8200      -23     

Files with missing lines	Coverage Δ
lib/internal/http2/core.js	95.19% <96.66%> (+<0.01%)	⬆️

... and 51 files with indirect coverage changes

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