[release/6.0][EventPipe] Fix reverse connection socket leaking to child processes...

[release/6.0][EventPipe] Fix reverse connection socket leaking to child processes. (#65768)

* [release/6.0][EventPipe] Fix reverse connection socket leaking to child processes.

Sockets were getting leaked upon accepting connections. This meant that child processes could cause
fully terminated tracing sessions and other IPC connections alive, causing clients to wait for input
indefinitely. This sets the CLOEXEC bits on the socket atomically upon accepting if the OS provides
the capability, falling back to a best effort fcntl on systems like macOS and x866 Android emulators.

Port of dotnet/runtime#65365 to release/6.0.

* Include well know cmake paths