Reduce overhead in ManagedNamedPipeClient during connection loop

The implementation of `NamedPipeClientStream` has some
 egregious use of `SpinOnce`:

https://github.com/dotnet/runtime/blob/d59af2cf097acb100ad6a9cba652be34be6f4a2e/src/libraries/System.IO.Pipes/src/System/IO/Pipes/NamedPipeClientStream.cs#L151-L155

This adds perceivable overhead to the connect process, which we really
don't want on a background thread. It is especially noticeable when
discord is not running and the reconnect process is constantly running
in the background.

To get around this, we can request a connect timeout of 0 ms from the underlying API.
Checking the implementations, this seems like a valid method, as long as
there is external retry logic in place (which there is in the local
class).

Tested on Windows, macOS and linux.

DiscordRPC/IO/ManagedNamedPipeClient.cs

@@ -140,6 +140,9 @@ private bool AttemptConnection(int pipe, bool isSandbox = false)
                 {
                     Logger.Info("Attempting to connect to '{0}'", pipename);
                     _stream = new NamedPipeClientStream(".", pipename, PipeDirection.InOut, PipeOptions.Asynchronous);
+
+                    // Intentionally use a timeout of 0 here to avoid spinlock overhead.
+                    // We are already performing local retry logic, so this is not required.
                     _stream.Connect(1000);
 
                     //Spin for a bit while we wait for it to finish connecting
@@ -378,7 +381,7 @@ public void Close()
                 return;
             }
 
-            //flush and dispose			
+            //flush and dispose
             try
             {
                 //Wait for the stream object to become available.