C#: Add Ide Connection library and server for the editor

This will be used for communicating between the Godot editor and external IDEs/editors, for things like opening files, triggering hot-reload and running the game with a debugger attached.

modules/mono/editor/GodotTools/GodotTools.IdeConnection/GodotIdeConnectionClient.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Net.Sockets;
+using System.Threading.Tasks;
+
+namespace GodotTools.IdeConnection
+{
+    public class GodotIdeConnectionClient : GodotIdeConnection
+    {
+        public GodotIdeConnectionClient(TcpClient tcpClient, Func<Message, bool> messageHandler)
+            : base(tcpClient, messageHandler)
+        {
+        }
+
+        protected override bool WriteHandshake()
+        {
+            return WriteLine(ClientHandshake);
+        }
+
+        protected override bool IsValidResponseHandshake(string handshakeLine)
+        {
+            return handshakeLine == ServerHandshake;
+        }
+    }
+}