[PR #9839/a9a0d84 backport][3.11] Implement zero copy writes in StreamWriter

[bdraco]

(cherry picked from commit a9a0d84)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.99%. Comparing base (c39032b) to head (542dfbd).
Report is 1 commits behind head on 3.11.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             3.11    #9847      +/-   ##
==========================================
+ Coverage   96.65%   97.99%   +1.34%     
==========================================
  Files         117      119       +2     
  Lines       36194    36349     +155     
  Branches     4319     4358      +39     
==========================================
+ Hits        34982    35620     +638     
+ Misses        996      545     -451     
+ Partials      216      184      -32     

Flag	Coverage Δ
CI-GHA	97.88% <100.00%> (+1.29%)	⬆️
OS-Linux	97.58% <100.00%> (?)
OS-Windows	94.43% <100.00%> (?)
OS-macOS	96.68% <100.00%> (+0.10%)	⬆️
Py-3.10.11	96.53% <100.00%> (+0.29%)	⬆️
Py-3.10.15	97.13% <100.00%> (?)
Py-3.11.10	97.15% <100.00%> (?)
Py-3.11.9	96.61% <100.00%> (+0.30%)	⬆️
Py-3.12.7	97.66% <100.00%> (+1.20%)	⬆️
Py-3.13.0	97.63% <100.00%> (?)
Py-3.9.13	96.46% <100.00%> (?)
Py-3.9.20	97.04% <100.00%> (?)
Py-pypy7.3.16	96.61% <100.00%> (?)
VM-macos	96.68% <100.00%> (+0.10%)	⬆️
VM-ubuntu	97.58% <100.00%> (?)
VM-windows	94.43% <100.00%> (?)

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[bdraco]

not sure how codecov is commenting on a failed test when the tests haven't even run yet

[codspeed-hq]

CodSpeed Performance Report

Merging #9847 will improve performances by 53.45%

_{Comparing patchback/backports/3.11/a9a0d849bd4ad65724710662e73f29f1e968bfe6/pr-9839 (542dfbd) with 3.11 (c39032b)}

Summary

⚡ 2 improvements
✅ 22 untouched benchmarks

Benchmarks breakdown

	Benchmark	3.11	patchback/backports/3.11/a9a0d849bd4ad65724710662e73f29f1e968bfe6/pr-9839	Change
⚡	test_one_hundred_get_requests_with_30000_chunked_payload[pyloop]	47.7 ms	43.5 ms	+9.59%
⚡	test_one_hundred_get_requests_with_512kib_chunked_payload[pyloop]	262 ms	170.7 ms	+53.45%