AwaitableSocketAsyncEventArgs should use UnsafeQueueUserWorkItem

[benaadams]

Might even be non-allocating if... dotnet/coreclr#21159 😉

/cc @stephentoub @davidfowl

[benaadams]

Needs #33637 first

[stephentoub]

Might even be non-allocating if

It basically already is. This path is only used if the operation completes asynchronously in the small window after we check IsCompleted but before we call UnsafeOnCompleted. Are you actually seeing non-trivial numbers of allocations there in traces?

[stephentoub]

Thanks, but as it stands this isn't a valid change. In the only path where this is used (noted above), we may actually need to flow ExecutionContext, e.g. socket.ReceiveAsync(...).GetAwaiter().OnCompleted(...).

[benaadams]

I missed the forceAsync: false on the other caller