Separate aiohttp.http_websocket into multiple files (#9542)

[bdraco]

(cherry picked from commit dd9a1fd)

[codspeed-hq]

CodSpeed Performance Report

Merging #9545 will not alter performance

_{Comparing patchback/backports/3.11/dd9a1fdf568de33bc444779ca5a273713223666c/pr-9542 (a80e57a) with 3.11 (37ceac7)}

Summary

✅ 4 untouched benchmarks

[codecov]

Codecov Report

Attention: Patch coverage is 98.31325% with 7 lines in your changes missing coverage. Please review.

Project coverage is 97.83%. Comparing base (37ceac7) to head (a80e57a).
Report is 276 commits behind head on 3.11.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
tests/test_websocket_parser.py	70.00%	2 Missing and 1 partial ⚠️
aiohttp/_websocket/reader.py	98.93%	1 Missing and 1 partial ⚠️
aiohttp/_websocket/helpers.py	98.71%	1 Missing ⚠️
aiohttp/_websocket/writer.py	98.82%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             3.11    #9545      +/-   ##
==========================================
- Coverage   97.85%   97.83%   -0.02%     
==========================================
  Files         109      113       +4     
  Lines       35271    35286      +15     
  Branches     4233     4233              
==========================================
+ Hits        34515    34523       +8     
- Misses        564      571       +7     
  Partials      192      192              

Flag	Coverage Δ
CI-GHA	97.72% <98.07%> (-0.02%)	⬇️
OS-Linux	97.41% <98.07%> (-0.02%)	⬇️
OS-Windows	94.81% <97.34%> (-0.05%)	⬇️
OS-macOS	97.11% <97.34%> (-0.02%)	⬇️
Py-3.10.11	96.97% <97.34%> (-0.02%)	⬇️
Py-3.10.15	96.90% <98.07%> (-0.02%)	⬇️
Py-3.11.10	96.97% <98.07%> (-0.03%)	⬇️
Py-3.11.9	97.05% <97.34%> (-0.02%)	⬇️
Py-3.12.7	97.45% <98.07%> (-0.02%)	⬇️
Py-3.13.0	97.43% <98.07%> (-0.02%)	⬇️
Py-3.9.13	96.88% <96.85%> (-0.02%)	⬇️
Py-3.9.20	96.82% <97.58%> (-0.02%)	⬇️
Py-pypy7.3.16	96.46% <97.10%> (+<0.01%)	⬆️
VM-macos	97.11% <97.34%> (-0.02%)	⬇️
VM-ubuntu	97.41% <98.07%> (-0.02%)	⬇️
VM-windows	94.81% <97.34%> (-0.05%)	⬇️

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[bdraco]

Almost done testing on production to make sure I didn't miss anything in the backport

[bdraco]

Downstream Home Assistant manual testing is OK and tests pass