[release/6.0] Fix compression

[github-actions]

Backport of #79412 to release/6.0

Fixes #77783

/cc @CarnaViire @greenEkatherine

Customer Impact

In .NET 6 we implemented WebSocket compression. It can be configured on per-connection and per-message basis. The per-message configuration is done via WebSocketMessageFlags, which are honored in WebSocket class (used mainly for server-side WebSockets), but are not exposed properly in ClientWebSocket class (used for client-side WebSockets).

The fix unifies behavior of ClientWebSocket with WebSocket. The fix does it by delegating to the encapsulated WebSocket instance (which already works correctly), instead of falling back to parent class implementation.

Regression?

No. The old behavior existed since introducing the feature in .NET 6.

Testing

CI + targeted test case.

Risk

Low risk - the change unifies behavior of ClientWebSocket with WebSocket. It does not add new code or behavior.

Also note that WebSocket compression is disabled by default.

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, to please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

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Issue Details

---

Backport of #79412 to release/6.0

/cc @CarnaViire @greenEkatherine

Customer Impact

Testing

Risk

IMPORTANT: Is this backport for a servicing release? If so and this change touches code that ships in a NuGet package, please make certain that you have added any necessary package authoring and gotten it explicitly reviewed.

Author:	github-actions[bot]
Assignees:	-
Labels:	area-System.Net, new-api-needs-documentation
Milestone:	-

[CarnaViire]

CI failures are unrelated.

runtime:

• Libraries Build windows net48 x86 Release failure is Expired Helix queue windows.10.amd64.client21h1.open failing 6.0 CI run #79646
• Libraries Test Run release coreclr windows x64 Debug failure is Microsoft.Extensions.FileProviders.Physical.PhysicalFilesWatcher.RaiseChangeEvents takes down process on an IO exception #71003 (PR Make PhysicalFileProvider polling more resilient to IO exceptions #72462) -- it was not backported to 6.0

runtime-staging:

• MacCatalyst errors are CI build failure: Build MacCatalyst x64 Release AllSubsets_Mono - XcodeBuildApp task failed unexpectedly - Could not find System.Runtime.Tests.app #78778, will be fixed by [release/6.0] Workaround MacCatalyst .app output path change in cmake 3.25 #79098

[karelz]

Approved by @SteveMCarroll via email on 2023/1/5 7:44am - adding Servicing-approved label.

• Email: "[Servicing-Consider] [6.0, 7.0] Fix per-message DisableCompression flag ..."

[carlossanlop]

Approved by Tactics (6.0.14).
Signed off by area owners.
CI failures investigated and considered unrelated.
OOB changes not needed - The involved src csproj does not have IsPackable=false.
Ready to merge.