Remove connection-specific headers for HTTP/2 and HTTP/3

[Kahbazi]

Spec for HTTP/2 and HTTP/3 states that connection-specific headers should be removed.

Such intermediaries SHOULD also remove other connection-specific fields, such as Keep-Alive, Proxy-Connection, Transfer-Encoding, and Upgrade, even if they are not nominated by the Connection field.

I want to create a PR for this issue. Is there any special way to add methods for clearing headers in HttpHeaders.Generated.cs since it's generated?
https://github.com/dotnet/aspnetcore/pull/24315/files/fb66a4e496ba49e3976731ad91be84fbafc9c936#diff-af588a349fd0f3044d4e05739c9c4293R8010-R8015

/cc @Tratcher

[Tratcher]

The source for that generated file is called KnownHeaders. You edit it like this:
https://github.com/dotnet/aspnetcore/pull/24315/files/fb66a4e496ba49e3976731ad91be84fbafc9c936#diff-9d6067e45fb1196b82da0a0e7c96040e
Then you run the CodeGenerator project. I usually just CTL+F5 to run it in VS, but you should be able to dotnet run it as well.
https://github.com/Kahbazi/AspNetCore/tree/fb66a4e496ba49e3976731ad91be84fbafc9c936/src/Servers/Kestrel/tools/CodeGenerator

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