quic: convert incoming :status header to number

[hallss93]

Fixes: #63557

Summary

When receiving HTTP/3 headers via QUIC, headers[':status'] was exposed as a
string. HTTP/2 converts the incoming :status pseudo-header to a number in
toHeaderObject() (lib/internal/http2/util.js). This mismatch makes it
awkward to port HTTP/2 code to HTTP/3.

Align HTTP/3 with HTTP/2 by converting :status to a number in
parseHeaderPairs() when building the header object from C++ name/value
pairs. This applies to initial response headers, informational (1xx)
headers (oninfo), and stream.headers.

Outgoing headers are unchanged: callers may still pass ':status': '200' or
':status': 200 when calling sendHeaders() / sendInformationalHeaders().

Test plan

• Update existing QUIC H3 tests to expect numeric :status on receive

• Add test/parallel/test-quic-h3-status-code-type.mjs covering 200, 204, and 404

• Run (with QUIC enabled):

  node --experimental-quic --experimental-stream-iter --no-warnings \
    test/parallel/test-quic-h3-status-code-type.mjs \
    test/parallel/test-quic-h3-header-validation.mjs \
    test/parallel/test-quic-h3-informational-headers.mjs \
    test/parallel/test-quic-h3-request-response.mjs

[nodejs-github-bot]

Review requested:

• @nodejs/quic

[pimterry]

@hallss93 Looks like the commit message here is failing the linting as it's not signed off, you'll need to update that with git commit --amend -s and then force push.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.32%. Comparing base (92f48f4) to head (f442353).
⚠️ Report is 22 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #63589      +/-   ##
==========================================
+ Coverage   90.31%   90.32%   +0.01%     
==========================================
  Files         730      730              
  Lines      234653   234658       +5     
  Branches    43952    43951       -1     
==========================================
+ Hits       211926   211959      +33     
+ Misses      14474    14430      -44     
- Partials     8253     8269      +16     

Files with missing lines	Coverage Δ
lib/internal/quic/quic.js	100.00% <100.00%> (ø)

... and 32 files with indirect coverage changes

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