fix(WebSocket): handle OSError upon send() + fix max_receive_queue == 0

[vytas7]

• Revise and rewrite parts of Lost Connections.
• Add unit tests (with full coverage) for the max_receive_queue == 0 case.
• Revise the test client if it could better simulate both behaviours depending on the simulated spec version.
• Add Uvicorn tests in test_asgi_servers.py that exercise the max_receive_queue == 0 case, and catches an error from the webserver's OSError upon send().
• Change E2E tests not to use buffering (since we know that use Uvicorn there).

Closes #2292.

[vytas7]

Note that I still need to revise the wording of our WebSocket docs, hence Draft (for now).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (87e0454) to head (db2c3c4).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #2324   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           63        63           
  Lines         7522      7539   +17     
  Branches      1275      1281    +6     
=========================================
+ Hits          7522      7539   +17     

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[CaselIT]

I'm waiting for this to exit draft. let me know if I should review before then

[vytas7]

Thanks @CaselIT , I haven't had much time to work on this, there are a couple of items remaining. Code-wise (not tests) I am not planning any more changes, so time permitting you could take a look at that part.
Documentation is ready too I think.

I need to add more tests, and morph newsfragments.

[vytas7]

@CaselIT maybe this PR is still not perfect (nothing is), but it is IMHO ready for review!

[CaselIT]

looks ok, left a suggestion