Server support (stdio) (#19)

* Server support (stdio)
* TestServer project
* Refactored McpClient class to extract shared endpoint logic (with McpServer) to a base class, McpJsonRpcEndpoint.
* Improved xmldoc comments for protocol types, mirroring specification schema comments.
* Update README.MD

src/mcpdotnet/Protocol/Transport/IMcpTransport.cs

@@ -1,32 +0,0 @@
-using System.Threading.Channels;
-using McpDotNet.Protocol.Messages;
-
-namespace McpDotNet.Protocol.Transport;
-/// <summary>
-/// Represents a transport mechanism for MCP communication.
-/// </summary>
-public interface IMcpTransport : IAsyncDisposable
-{
-    /// <summary>
-    /// Gets whether the transport is currently connected.
-    /// </summary>
-    bool IsConnected { get; }
-
-    /// <summary>
-    /// Channel for receiving messages from the transport.
-    /// </summary>
-    ChannelReader<IJsonRpcMessage> MessageReader { get; }
-
-    /// <summary>
-    /// Establishes the transport connection.
-    /// </summary>
-    /// <param name="cancellationToken">Token to cancel the operation.</param>
-    Task ConnectAsync(CancellationToken cancellationToken = default);
-
-    /// <summary>
-    /// Sends a message through the transport.
-    /// </summary>
-    /// <param name="message">The message to send.</param>
-    /// <param name="cancellationToken">Token to cancel the operation.</param>
-    Task SendMessageAsync(IJsonRpcMessage message, CancellationToken cancellationToken = default);
-}