Fix some issues with Native AOT (#130)

* Fix some issues with Native AOT

- An anonymous type was being used in McpClient for the initialize result message. Switched to use the type for that purpose that already existed.
- A bunch of the request params / result types were not in the source context or referenced from types that were or from custom converters. Added all the request/result types to the context.
- Improved the warning message for WithTools.

src/ModelContextProtocol/Protocol/Messages/JsonRpcRequest.cs

@@ -0,0 +1,33 @@
+using System.Text.Json.Serialization;
+
+namespace ModelContextProtocol.Protocol.Messages;
+
+/// <summary>
+/// A request message in the JSON-RPC protocol.
+/// </summary>
+public record JsonRpcRequest : IJsonRpcMessageWithId
+{
+    /// <summary>
+    /// JSON-RPC protocol version. Always "2.0".
+    /// </summary>
+    [JsonPropertyName("jsonrpc")]
+    public string JsonRpc { get; init; } = "2.0";
+
+    /// <summary>
+    /// Request identifier. Must be a string or number and unique within the session.
+    /// </summary>
+    [JsonPropertyName("id")]
+    public RequestId Id { get; set; }
+
+    /// <summary>
+    /// Name of the method to invoke.
+    /// </summary>
+    [JsonPropertyName("method")]
+    public required string Method { get; init; }
+
+    /// <summary>
+    /// Optional parameters for the method.
+    /// </summary>
+    [JsonPropertyName("params")]
+    public object? Params { get; init; }
+}