Create WireMock.Net.ProtoBuf project (#1350)

* Create WireMock.Net.ProtoBuf project

* ok

* Update Directory.Build.props

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/WireMock.Net.Shared/ResponseBuilders/IResponseBuilder.cs

@@ -0,0 +1,19 @@
+// Copyright © WireMock.Net
+
+namespace WireMock.ResponseBuilders;
+
+/// <summary>
+/// The ResponseBuilder interface.
+/// </summary>
+public interface IResponseBuilder : IProxyResponseBuilder
+{
+    /// <summary>
+    /// The link back to the mapping.
+    /// </summary>
+    IMapping Mapping { get; }
+
+    /// <summary>
+    /// Gets the response message.
+    /// </summary>
+    IResponseMessage ResponseMessage { get; }
+}