Fix stdio client transport CLI argument escaping. (#811)

* Fix stdio client transport CLI argument escaping.

* Fix failing Windows test.

* Add more test cases and refine escaping logic.

* Fix test failures in mono

* Style fixes

* Tweak stdio test

* Tweak tests further

tests/ModelContextProtocol.Tests/PlatformDetection.cs

@@ -1,6 +1,9 @@
+using System.Runtime.InteropServices;
+
 namespace ModelContextProtocol.Tests;
 
 internal static class PlatformDetection
 {
     public static bool IsMonoRuntime { get; } = Type.GetType("Mono.Runtime") is not null;
+    public static bool IsWindows { get; } = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
 }