Add sockets/libuv to kestrel test namespaces (#35244)

...Kestrel/test/FunctionalTests/ConnectionMiddlewareTests.cs

...vers/Kestrel/test/FunctionalTests/Http2/HandshakeTests.cs

...rvers/Kestrel/test/FunctionalTests/Http2/ShutdownTests.cs

...Servers/Kestrel/test/FunctionalTests/ListenHandleTests.cs

...Kestrel/test/FunctionalTests/MaxRequestBufferSizeTests.cs

src/Servers/Kestrel/test/FunctionalTests/RequestTests.cs

src/Servers/Kestrel/test/FunctionalTests/ResponseTests.cs

...rs/Kestrel/test/FunctionalTests/UnixDomainSocketsTests.cs

...strel/test/Sockets.FunctionalTests/SocketTranspotTests.cs

...st/Sockets.FunctionalTests/Sockets.FunctionalTests.csproj